diff -r 25731d245eda -r 487ca37bb0c7 web/res/js/backbone.js
--- a/web/res/js/backbone.js	Wed Dec 11 10:17:08 2019 +0100
+++ b/web/res/js/backbone.js	Wed Dec 11 11:02:15 2019 +0100
@@ -1,6 +1,6 @@
-//     Backbone.js 1.2.3
+//     Backbone.js 1.4.0
 
-//     (c) 2010-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
+//     (c) 2010-2019 Jeremy Ashkenas and DocumentCloud
 //     Backbone may be freely distributed under the MIT license.
 //     For all details and documentation:
 //     http://backbonejs.org
@@ -9,8 +9,8 @@
 
   // Establish the root object, `window` (`self`) in the browser, or `global` on the server.
   // We use `self` instead of `window` for `WebWorker` support.
-  var root = (typeof self == 'object' && self.self == self && self) ||
-            (typeof global == 'object' && global.global == global && global);
+  var root = typeof self == 'object' && self.self === self && self ||
+            typeof global == 'object' && global.global === global && global;
 
   // Set up Backbone appropriately for the environment. Start with AMD.
   if (typeof define === 'function' && define.amd) {
@@ -23,15 +23,15 @@
   // Next for Node.js or CommonJS. jQuery may not be needed as a module.
   } else if (typeof exports !== 'undefined') {
     var _ = require('underscore'), $;
-    try { $ = require('jquery'); } catch(e) {}
+    try { $ = require('jquery'); } catch (e) {}
     factory(root, exports, _, $);
 
   // Finally, as a browser global.
   } else {
-    root.Backbone = factory(root, {}, root._, (root.jQuery || root.Zepto || root.ender || root.$));
+    root.Backbone = factory(root, {}, root._, root.jQuery || root.Zepto || root.ender || root.$);
   }
 
-}(function(root, Backbone, _, $) {
+})(function(root, Backbone, _, $) {
 
   // Initial Setup
   // -------------
@@ -44,7 +44,7 @@
   var slice = Array.prototype.slice;
 
   // Current version of the library. Keep in sync with `package.json`.
-  Backbone.VERSION = '1.2.3';
+  Backbone.VERSION = '1.4.0';
 
   // For Backbone's purposes, jQuery, Zepto, Ender, or My Library (kidding) owns
   // the `$` variable.
@@ -68,54 +68,6 @@
   // form param named `model`.
   Backbone.emulateJSON = false;
 
-  // Proxy Backbone class methods to Underscore functions, wrapping the model's
-  // `attributes` object or collection's `models` array behind the scenes.
-  //
-  // collection.filter(function(model) { return model.get('age') > 10 });
-  // collection.each(this.addView);
-  //
-  // `Function#apply` can be slow so we use the method's arg count, if we know it.
-  var addMethod = function(length, method, attribute) {
-    switch (length) {
-      case 1: return function() {
-        return _[method](this[attribute]);
-      };
-      case 2: return function(value) {
-        return _[method](this[attribute], value);
-      };
-      case 3: return function(iteratee, context) {
-        return _[method](this[attribute], cb(iteratee, this), context);
-      };
-      case 4: return function(iteratee, defaultVal, context) {
-        return _[method](this[attribute], cb(iteratee, this), defaultVal, context);
-      };
-      default: return function() {
-        var args = slice.call(arguments);
-        args.unshift(this[attribute]);
-        return _[method].apply(_, args);
-      };
-    }
-  };
-  var addUnderscoreMethods = function(Class, methods, attribute) {
-    _.each(methods, function(length, method) {
-      if (_[method]) Class.prototype[method] = addMethod(length, method, attribute);
-    });
-  };
-
-  // Support `collection.sortBy('attr')` and `collection.findWhere({id: 1})`.
-  var cb = function(iteratee, instance) {
-    if (_.isFunction(iteratee)) return iteratee;
-    if (_.isObject(iteratee) && !instance._isModel(iteratee)) return modelMatcher(iteratee);
-    if (_.isString(iteratee)) return function(model) { return model.get(iteratee); };
-    return iteratee;
-  };
-  var modelMatcher = function(attrs) {
-    var matcher = _.matches(attrs);
-    return function(model) {
-      return matcher(model.attributes);
-    };
-  };
-
   // Backbone.Events
   // ---------------
 
@@ -134,6 +86,9 @@
   // Regular expression used to split event strings.
   var eventSplitter = /\s+/;
 
+  // A private global variable to share between listeners and listenees.
+  var _listening;
+
   // Iterates over the standard `event, callback` (as well as the fancy multiple
   // space-separated events `"change blur", callback` and jQuery-style event
   // maps `{event: callback}`).
@@ -146,7 +101,7 @@
         events = eventsApi(iteratee, events, names[i], name[names[i]], opts);
       }
     } else if (name && eventSplitter.test(name)) {
-      // Handle space separated event names by delegating them individually.
+      // Handle space-separated event names by delegating them individually.
       for (names = name.split(eventSplitter); i < names.length; i++) {
         events = iteratee(events, names[i], callback, opts);
       }
@@ -160,43 +115,47 @@
   // Bind an event to a `callback` function. Passing `"all"` will bind
   // the callback to all events fired.
   Events.on = function(name, callback, context) {
-    return internalOn(this, name, callback, context);
-  };
-
-  // Guard the `listening` argument from the public API.
-  var internalOn = function(obj, name, callback, context, listening) {
-    obj._events = eventsApi(onApi, obj._events || {}, name, callback, {
-        context: context,
-        ctx: obj,
-        listening: listening
+    this._events = eventsApi(onApi, this._events || {}, name, callback, {
+      context: context,
+      ctx: this,
+      listening: _listening
     });
 
-    if (listening) {
-      var listeners = obj._listeners || (obj._listeners = {});
-      listeners[listening.id] = listening;
+    if (_listening) {
+      var listeners = this._listeners || (this._listeners = {});
+      listeners[_listening.id] = _listening;
+      // Allow the listening to use a counter, instead of tracking
+      // callbacks for library interop
+      _listening.interop = false;
     }
 
-    return obj;
+    return this;
   };
 
   // Inversion-of-control versions of `on`. Tell *this* object to listen to
   // an event in another object... keeping track of what it's listening to
   // for easier unbinding later.
-  Events.listenTo =  function(obj, name, callback) {
+  Events.listenTo = function(obj, name, callback) {
     if (!obj) return this;
     var id = obj._listenId || (obj._listenId = _.uniqueId('l'));
     var listeningTo = this._listeningTo || (this._listeningTo = {});
-    var listening = listeningTo[id];
+    var listening = _listening = listeningTo[id];
 
     // This object is not listening to any other events on `obj` yet.
     // Setup the necessary references to track the listening callbacks.
     if (!listening) {
-      var thisId = this._listenId || (this._listenId = _.uniqueId('l'));
-      listening = listeningTo[id] = {obj: obj, objId: id, id: thisId, listeningTo: listeningTo, count: 0};
+      this._listenId || (this._listenId = _.uniqueId('l'));
+      listening = _listening = listeningTo[id] = new Listening(this, obj);
     }
 
-    // Bind callbacks on obj, and keep track of them on listening.
-    internalOn(obj, name, callback, this, listening);
+    // Bind callbacks on obj.
+    var error = tryCatchOn(obj, name, callback, this);
+    _listening = void 0;
+
+    if (error) throw error;
+    // If the target obj is not Backbone.Events, track events manually.
+    if (listening.interop) listening.on(name, callback);
+
     return this;
   };
 
@@ -207,32 +166,42 @@
       var context = options.context, ctx = options.ctx, listening = options.listening;
       if (listening) listening.count++;
 
-      handlers.push({ callback: callback, context: context, ctx: context || ctx, listening: listening });
+      handlers.push({callback: callback, context: context, ctx: context || ctx, listening: listening});
     }
     return events;
   };
 
+  // An try-catch guarded #on function, to prevent poisoning the global
+  // `_listening` variable.
+  var tryCatchOn = function(obj, name, callback, context) {
+    try {
+      obj.on(name, callback, context);
+    } catch (e) {
+      return e;
+    }
+  };
+
   // Remove one or many callbacks. If `context` is null, removes all
   // callbacks with that function. If `callback` is null, removes all
   // callbacks for the event. If `name` is null, removes all bound
   // callbacks for all events.
-  Events.off =  function(name, callback, context) {
+  Events.off = function(name, callback, context) {
     if (!this._events) return this;
     this._events = eventsApi(offApi, this._events, name, callback, {
-        context: context,
-        listeners: this._listeners
+      context: context,
+      listeners: this._listeners
     });
+
     return this;
   };
 
   // Tell this object to stop listening to either specific events ... or
   // to every object it's currently listening to.
-  Events.stopListening =  function(obj, name, callback) {
+  Events.stopListening = function(obj, name, callback) {
     var listeningTo = this._listeningTo;
     if (!listeningTo) return this;
 
     var ids = obj ? [obj._listenId] : _.keys(listeningTo);
-
     for (var i = 0; i < ids.length; i++) {
       var listening = listeningTo[ids[i]];
 
@@ -241,6 +210,7 @@
       if (!listening) break;
 
       listening.obj.off(name, callback, this);
+      if (listening.interop) listening.off(name, callback);
     }
     if (_.isEmpty(listeningTo)) this._listeningTo = void 0;
 
@@ -251,21 +221,18 @@
   var offApi = function(events, name, callback, options) {
     if (!events) return;
 
-    var i = 0, listening;
     var context = options.context, listeners = options.listeners;
+    var i = 0, names;
 
-    // Delete all events listeners and "drop" events.
-    if (!name && !callback && !context) {
-      var ids = _.keys(listeners);
-      for (; i < ids.length; i++) {
-        listening = listeners[ids[i]];
-        delete listeners[listening.id];
-        delete listening.listeningTo[listening.objId];
+    // Delete all event listeners and "drop" events.
+    if (!name && !context && !callback) {
+      for (names = _.keys(listeners); i < names.length; i++) {
+        listeners[names[i]].cleanup();
       }
       return;
     }
 
-    var names = name ? [name] : _.keys(events);
+    names = name ? [name] : _.keys(events);
     for (; i < names.length; i++) {
       name = names[i];
       var handlers = events[name];
@@ -273,7 +240,7 @@
       // Bail out if there are no events stored.
       if (!handlers) break;
 
-      // Replace events if there are any remaining.  Otherwise, clean up.
+      // Find any remaining events.
       var remaining = [];
       for (var j = 0; j < handlers.length; j++) {
         var handler = handlers[j];
@@ -284,38 +251,37 @@
         ) {
           remaining.push(handler);
         } else {
-          listening = handler.listening;
-          if (listening && --listening.count === 0) {
-            delete listeners[listening.id];
-            delete listening.listeningTo[listening.objId];
-          }
+          var listening = handler.listening;
+          if (listening) listening.off(name, callback);
         }
       }
 
-      // Update tail event if the list has any events.  Otherwise, clean up.
+      // Replace events if there are any remaining.  Otherwise, clean up.
       if (remaining.length) {
         events[name] = remaining;
       } else {
         delete events[name];
       }
     }
-    if (_.size(events)) return events;
+
+    return events;
   };
 
   // Bind an event to only be triggered a single time. After the first time
   // the callback is invoked, its listener will be removed. If multiple events
   // are passed in using the space-separated syntax, the handler will fire
   // once for each event, not once for a combination of all events.
-  Events.once =  function(name, callback, context) {
+  Events.once = function(name, callback, context) {
     // Map the event into a `{event: once}` object.
-    var events = eventsApi(onceMap, {}, name, callback, _.bind(this.off, this));
-    return this.on(events, void 0, context);
+    var events = eventsApi(onceMap, {}, name, callback, this.off.bind(this));
+    if (typeof name === 'string' && context == null) callback = void 0;
+    return this.on(events, callback, context);
   };
 
   // Inversion-of-control versions of `once`.
-  Events.listenToOnce =  function(obj, name, callback) {
+  Events.listenToOnce = function(obj, name, callback) {
     // Map the event into a `{event: once}` object.
-    var events = eventsApi(onceMap, {}, name, callback, _.bind(this.stopListening, this, obj));
+    var events = eventsApi(onceMap, {}, name, callback, this.stopListening.bind(this, obj));
     return this.listenTo(obj, events);
   };
 
@@ -336,7 +302,7 @@
   // passed the same arguments as `trigger` is, apart from the event name
   // (unless you're listening on `"all"`, which will cause your callback to
   // receive the true name of the event as the first argument).
-  Events.trigger =  function(name) {
+  Events.trigger = function(name) {
     if (!this._events) return this;
 
     var length = Math.max(0, arguments.length - 1);
@@ -348,7 +314,7 @@
   };
 
   // Handles triggering the appropriate event callbacks.
-  var triggerApi = function(objEvents, name, cb, args) {
+  var triggerApi = function(objEvents, name, callback, args) {
     if (objEvents) {
       var events = objEvents[name];
       var allEvents = objEvents.all;
@@ -373,6 +339,44 @@
     }
   };
 
+  // A listening class that tracks and cleans up memory bindings
+  // when all callbacks have been offed.
+  var Listening = function(listener, obj) {
+    this.id = listener._listenId;
+    this.listener = listener;
+    this.obj = obj;
+    this.interop = true;
+    this.count = 0;
+    this._events = void 0;
+  };
+
+  Listening.prototype.on = Events.on;
+
+  // Offs a callback (or several).
+  // Uses an optimized counter if the listenee uses Backbone.Events.
+  // Otherwise, falls back to manual tracking to support events
+  // library interop.
+  Listening.prototype.off = function(name, callback) {
+    var cleanup;
+    if (this.interop) {
+      this._events = eventsApi(offApi, this._events, name, callback, {
+        context: void 0,
+        listeners: void 0
+      });
+      cleanup = !this._events;
+    } else {
+      this.count--;
+      cleanup = this.count === 0;
+    }
+    if (cleanup) this.cleanup();
+  };
+
+  // Cleans up memory bindings between the listener and the listenee.
+  Listening.prototype.cleanup = function() {
+    delete this.listener._listeningTo[this.obj._listenId];
+    if (!this.interop) delete this.obj._listeners[this.id];
+  };
+
   // Aliases for backwards compatibility.
   Events.bind   = Events.on;
   Events.unbind = Events.off;
@@ -394,11 +398,13 @@
   var Model = Backbone.Model = function(attributes, options) {
     var attrs = attributes || {};
     options || (options = {});
+    this.preinitialize.apply(this, arguments);
     this.cid = _.uniqueId(this.cidPrefix);
     this.attributes = {};
     if (options.collection) this.collection = options.collection;
     if (options.parse) attrs = this.parse(attrs, options) || {};
-    attrs = _.defaults({}, attrs, _.result(this, 'defaults'));
+    var defaults = _.result(this, 'defaults');
+    attrs = _.defaults(_.extend({}, defaults, attrs), defaults);
     this.set(attrs, options);
     this.changed = {};
     this.initialize.apply(this, arguments);
@@ -421,6 +427,10 @@
     // You may want to override this if you're experiencing name clashes with model ids.
     cidPrefix: 'c',
 
+    // preinitialize is an empty function by default. You can override it with a function
+    // or object.  preinitialize will run before any instantiation logic is run in the Model.
+    preinitialize: function(){},
+
     // Initialize is an empty function by default. Override it with your own
     // initialization logic.
     initialize: function(){},
@@ -506,7 +516,7 @@
       }
 
       // Update the `id`.
-      this.id = this.get(this.idAttribute);
+      if (this.idAttribute in attrs) this.id = this.get(this.idAttribute);
 
       // Trigger all relevant attribute changes.
       if (!silent) {
@@ -561,12 +571,14 @@
       if (!diff) return this.hasChanged() ? _.clone(this.changed) : false;
       var old = this._changing ? this._previousAttributes : this.attributes;
       var changed = {};
+      var hasChanged;
       for (var attr in diff) {
         var val = diff[attr];
         if (_.isEqual(old[attr], val)) continue;
         changed[attr] = val;
+        hasChanged = true;
       }
-      return _.size(changed) ? changed : false;
+      return hasChanged ? changed : false;
     },
 
     // Get the previous value of an attribute, recorded at the time the last
@@ -619,8 +631,8 @@
       // the model will be valid when the attributes, if any, are set.
       if (attrs && !wait) {
         if (!this.set(attrs, options)) return false;
-      } else {
-        if (!this._validate(attrs, options)) return false;
+      } else if (!this._validate(attrs, options)) {
+        return false;
       }
 
       // After a successful server-side save, the client is (optionally)
@@ -642,7 +654,7 @@
       // Set temporary attributes if `{wait: true}` to properly find new ids.
       if (attrs && wait) this.attributes = _.extend({}, attributes, attrs);
 
-      var method = this.isNew() ? 'create' : (options.patch ? 'patch' : 'update');
+      var method = this.isNew() ? 'create' : options.patch ? 'patch' : 'update';
       if (method === 'patch' && !options.attrs) options.attrs = attrs;
       var xhr = this.sync(method, this, options);
 
@@ -714,7 +726,7 @@
 
     // Check if the model is currently in a valid state.
     isValid: function(options) {
-      return this._validate({}, _.defaults({validate: true}, options));
+      return this._validate({}, _.extend({}, options, {validate: true}));
     },
 
     // Run validation against the next complete set of model attributes,
@@ -730,14 +742,6 @@
 
   });
 
-  // Underscore methods that we want to implement on the Model, mapped to the
-  // number of arguments they take.
-  var modelMethods = { keys: 1, values: 1, pairs: 1, invert: 1, pick: 0,
-      omit: 0, chain: 1, isEmpty: 1 };
-
-  // Mix in each Underscore method as a proxy to `Model#attributes`.
-  addUnderscoreMethods(Model, modelMethods, 'attributes');
-
   // Backbone.Collection
   // -------------------
 
@@ -753,6 +757,7 @@
   // its models in sort order, as they're added and removed.
   var Collection = Backbone.Collection = function(models, options) {
     options || (options = {});
+    this.preinitialize.apply(this, arguments);
     if (options.model) this.model = options.model;
     if (options.comparator !== void 0) this.comparator = options.comparator;
     this._reset();
@@ -769,7 +774,8 @@
     at = Math.min(Math.max(at, 0), array.length);
     var tail = Array(array.length - at);
     var length = insert.length;
-    for (var i = 0; i < tail.length; i++) tail[i] = array[i + at];
+    var i;
+    for (i = 0; i < tail.length; i++) tail[i] = array[i + at];
     for (i = 0; i < length; i++) array[i + at] = insert[i];
     for (i = 0; i < tail.length; i++) array[i + length + at] = tail[i];
   };
@@ -781,6 +787,11 @@
     // This should be overridden in most cases.
     model: Model,
 
+
+    // preinitialize is an empty function by default. You can override it with a function
+    // or object.  preinitialize will run before any instantiation logic is run in the Collection.
+    preinitialize: function(){},
+
     // Initialize is an empty function by default. Override it with your own
     // initialization logic.
     initialize: function(){},
@@ -807,9 +818,12 @@
     remove: function(models, options) {
       options = _.extend({}, options);
       var singular = !_.isArray(models);
-      models = singular ? [models] : _.clone(models);
+      models = singular ? [models] : models.slice();
       var removed = this._removeModels(models, options);
-      if (!options.silent && removed) this.trigger('update', this, options);
+      if (!options.silent && removed.length) {
+        options.changes = {added: [], merged: [], removed: removed};
+        this.trigger('update', this, options);
+      }
       return singular ? removed[0] : removed;
     },
 
@@ -820,18 +834,22 @@
     set: function(models, options) {
       if (models == null) return;
 
-      options = _.defaults({}, options, setOptions);
-      if (options.parse && !this._isModel(models)) models = this.parse(models, options);
+      options = _.extend({}, setOptions, options);
+      if (options.parse && !this._isModel(models)) {
+        models = this.parse(models, options) || [];
+      }
 
       var singular = !_.isArray(models);
       models = singular ? [models] : models.slice();
 
       var at = options.at;
       if (at != null) at = +at;
+      if (at > this.length) at = this.length;
       if (at < 0) at += this.length + 1;
 
       var set = [];
       var toAdd = [];
+      var toMerge = [];
       var toRemove = [];
       var modelMap = {};
 
@@ -840,13 +858,13 @@
       var remove = options.remove;
 
       var sort = false;
-      var sortable = this.comparator && (at == null) && options.sort !== false;
+      var sortable = this.comparator && at == null && options.sort !== false;
       var sortAttr = _.isString(this.comparator) ? this.comparator : null;
 
       // Turn bare objects into model references, and prevent invalid models
       // from being added.
-      var model;
-      for (var i = 0; i < models.length; i++) {
+      var model, i;
+      for (i = 0; i < models.length; i++) {
         model = models[i];
 
         // If a duplicate is found, prevent it from being added and
@@ -857,6 +875,7 @@
             var attrs = this._isModel(model) ? model.attributes : model;
             if (options.parse) attrs = existing.parse(attrs, options);
             existing.set(attrs, options);
+            toMerge.push(existing);
             if (sortable && !sort) sort = existing.hasChanged(sortAttr);
           }
           if (!modelMap[existing.cid]) {
@@ -890,8 +909,8 @@
       var orderChanged = false;
       var replace = !sortable && add && remove;
       if (set.length && replace) {
-        orderChanged = this.length != set.length || _.some(this.models, function(model, index) {
-          return model !== set[index];
+        orderChanged = this.length !== set.length || _.some(this.models, function(m, index) {
+          return m !== set[index];
         });
         this.models.length = 0;
         splice(this.models, set, 0);
@@ -905,7 +924,7 @@
       // Silently sort the collection if appropriate.
       if (sort) this.sort({silent: true});
 
-      // Unless silenced, it's time to fire all appropriate add/sort events.
+      // Unless silenced, it's time to fire all appropriate add/sort/update events.
       if (!options.silent) {
         for (i = 0; i < toAdd.length; i++) {
           if (at != null) options.index = at + i;
@@ -913,7 +932,14 @@
           model.trigger('add', model, this, options);
         }
         if (sort || orderChanged) this.trigger('sort', this, options);
-        if (toAdd.length || toRemove.length) this.trigger('update', this, options);
+        if (toAdd.length || toRemove.length || toMerge.length) {
+          options.changes = {
+            added: toAdd,
+            removed: toRemove,
+            merged: toMerge
+          };
+          this.trigger('update', this, options);
+        }
       }
 
       // Return the added (or merged) model (or models).
@@ -963,11 +989,18 @@
       return slice.apply(this.models, arguments);
     },
 
-    // Get a model from the set by id.
+    // Get a model from the set by id, cid, model object with id or cid
+    // properties, or an attributes object that is transformed through modelId.
     get: function(obj) {
       if (obj == null) return void 0;
-      var id = this.modelId(this._isModel(obj) ? obj.attributes : obj);
-      return this._byId[obj] || this._byId[id] || this._byId[obj.cid];
+      return this._byId[obj] ||
+        this._byId[this.modelId(this._isModel(obj) ? obj.attributes : obj)] ||
+        obj.cid && this._byId[obj.cid];
+    },
+
+    // Returns `true` if the model is in the collection.
+    has: function(obj) {
+      return this.get(obj) != null;
     },
 
     // Get the model at the given index.
@@ -997,7 +1030,7 @@
       options || (options = {});
 
       var length = comparator.length;
-      if (_.isFunction(comparator)) comparator = _.bind(comparator, this);
+      if (_.isFunction(comparator)) comparator = comparator.bind(this);
 
       // Run sort based on type of `comparator`.
       if (length === 1 || _.isString(comparator)) {
@@ -1011,7 +1044,7 @@
 
     // Pluck an attribute from each model in the collection.
     pluck: function(attr) {
-      return _.invoke(this.models, 'get', attr);
+      return this.map(attr + '');
     },
 
     // Fetch the default set of models for this collection, resetting the
@@ -1042,9 +1075,9 @@
       if (!wait) this.add(model, options);
       var collection = this;
       var success = options.success;
-      options.success = function(model, resp, callbackOpts) {
-        if (wait) collection.add(model, callbackOpts);
-        if (success) success.call(callbackOpts.context, model, resp, callbackOpts);
+      options.success = function(m, resp, callbackOpts) {
+        if (wait) collection.add(m, callbackOpts);
+        if (success) success.call(callbackOpts.context, m, resp, callbackOpts);
       };
       model.save(null, options);
       return model;
@@ -1065,10 +1098,25 @@
     },
 
     // Define how to uniquely identify models in the collection.
-    modelId: function (attrs) {
+    modelId: function(attrs) {
       return attrs[this.model.prototype.idAttribute || 'id'];
     },
 
+    // Get an iterator of all models in this collection.
+    values: function() {
+      return new CollectionIterator(this, ITERATOR_VALUES);
+    },
+
+    // Get an iterator of all model IDs in this collection.
+    keys: function() {
+      return new CollectionIterator(this, ITERATOR_KEYS);
+    },
+
+    // Get an iterator of all [ID, model] tuples in this collection.
+    entries: function() {
+      return new CollectionIterator(this, ITERATOR_KEYSVALUES);
+    },
+
     // Private method to reset all internal state. Called when the collection
     // is first initialized or reset.
     _reset: function() {
@@ -1103,6 +1151,12 @@
         this.models.splice(index, 1);
         this.length--;
 
+        // Remove references before triggering 'remove' event to prevent an
+        // infinite loop. #3693
+        delete this._byId[model.cid];
+        var id = this.modelId(model.attributes);
+        if (id != null) delete this._byId[id];
+
         if (!options.silent) {
           options.index = index;
           model.trigger('remove', model, this, options);
@@ -1111,12 +1165,12 @@
         removed.push(model);
         this._removeReference(model, options);
       }
-      return removed.length ? removed : false;
+      return removed;
     },
 
     // Method for checking whether an object should be considered a model for
     // the purposes of adding to the collection.
-    _isModel: function (model) {
+    _isModel: function(model) {
       return model instanceof Model;
     },
 
@@ -1142,14 +1196,16 @@
     // events simply proxy through. "add" and "remove" events that originate
     // in other collections are ignored.
     _onModelEvent: function(event, model, collection, options) {
-      if ((event === 'add' || event === 'remove') && collection !== this) return;
-      if (event === 'destroy') this.remove(model, options);
-      if (event === 'change') {
-        var prevId = this.modelId(model.previousAttributes());
-        var id = this.modelId(model.attributes);
-        if (prevId !== id) {
-          if (prevId != null) delete this._byId[prevId];
-          if (id != null) this._byId[id] = model;
+      if (model) {
+        if ((event === 'add' || event === 'remove') && collection !== this) return;
+        if (event === 'destroy') this.remove(model, options);
+        if (event === 'change') {
+          var prevId = this.modelId(model.previousAttributes());
+          var id = this.modelId(model.attributes);
+          if (prevId !== id) {
+            if (prevId != null) delete this._byId[prevId];
+            if (id != null) this._byId[id] = model;
+          }
         }
       }
       this.trigger.apply(this, arguments);
@@ -1157,20 +1213,71 @@
 
   });
 
-  // Underscore methods that we want to implement on the Collection.
-  // 90% of the core usefulness of Backbone Collections is actually implemented
-  // right here:
-  var collectionMethods = { forEach: 3, each: 3, map: 3, collect: 3, reduce: 4,
-      foldl: 4, inject: 4, reduceRight: 4, foldr: 4, find: 3, detect: 3, filter: 3,
-      select: 3, reject: 3, every: 3, all: 3, some: 3, any: 3, include: 3, includes: 3,
-      contains: 3, invoke: 0, max: 3, min: 3, toArray: 1, size: 1, first: 3,
-      head: 3, take: 3, initial: 3, rest: 3, tail: 3, drop: 3, last: 3,
-      without: 0, difference: 0, indexOf: 3, shuffle: 1, lastIndexOf: 3,
-      isEmpty: 1, chain: 1, sample: 3, partition: 3, groupBy: 3, countBy: 3,
-      sortBy: 3, indexBy: 3};
+  // Defining an @@iterator method implements JavaScript's Iterable protocol.
+  // In modern ES2015 browsers, this value is found at Symbol.iterator.
+  /* global Symbol */
+  var $$iterator = typeof Symbol === 'function' && Symbol.iterator;
+  if ($$iterator) {
+    Collection.prototype[$$iterator] = Collection.prototype.values;
+  }
+
+  // CollectionIterator
+  // ------------------
+
+  // A CollectionIterator implements JavaScript's Iterator protocol, allowing the
+  // use of `for of` loops in modern browsers and interoperation between
+  // Backbone.Collection and other JavaScript functions and third-party libraries
+  // which can operate on Iterables.
+  var CollectionIterator = function(collection, kind) {
+    this._collection = collection;
+    this._kind = kind;
+    this._index = 0;
+  };
+
+  // This "enum" defines the three possible kinds of values which can be emitted
+  // by a CollectionIterator that correspond to the values(), keys() and entries()
+  // methods on Collection, respectively.
+  var ITERATOR_VALUES = 1;
+  var ITERATOR_KEYS = 2;
+  var ITERATOR_KEYSVALUES = 3;
 
-  // Mix in each Underscore method as a proxy to `Collection#models`.
-  addUnderscoreMethods(Collection, collectionMethods, 'models');
+  // All Iterators should themselves be Iterable.
+  if ($$iterator) {
+    CollectionIterator.prototype[$$iterator] = function() {
+      return this;
+    };
+  }
+
+  CollectionIterator.prototype.next = function() {
+    if (this._collection) {
+
+      // Only continue iterating if the iterated collection is long enough.
+      if (this._index < this._collection.length) {
+        var model = this._collection.at(this._index);
+        this._index++;
+
+        // Construct a value depending on what kind of values should be iterated.
+        var value;
+        if (this._kind === ITERATOR_VALUES) {
+          value = model;
+        } else {
+          var id = this._collection.modelId(model.attributes);
+          if (this._kind === ITERATOR_KEYS) {
+            value = id;
+          } else { // ITERATOR_KEYSVALUES
+            value = [id, model];
+          }
+        }
+        return {value: value, done: false};
+      }
+
+      // Once exhausted, remove the reference to the collection so future
+      // calls to the next method always return done.
+      this._collection = void 0;
+    }
+
+    return {value: void 0, done: true};
+  };
 
   // Backbone.View
   // -------------
@@ -1187,6 +1294,7 @@
   // if an existing element is not provided...
   var View = Backbone.View = function(options) {
     this.cid = _.uniqueId('view');
+    this.preinitialize.apply(this, arguments);
     _.extend(this, _.pick(options, viewOptions));
     this._ensureElement();
     this.initialize.apply(this, arguments);
@@ -1210,6 +1318,10 @@
       return this.$el.find(selector);
     },
 
+    // preinitialize is an empty function by default. You can override it with a function
+    // or object.  preinitialize will run before any instantiation logic is run in the View
+    preinitialize: function(){},
+
     // Initialize is an empty function by default. Override it with your own
     // initialization logic.
     initialize: function(){},
@@ -1277,7 +1389,7 @@
         if (!_.isFunction(method)) method = this[method];
         if (!method) continue;
         var match = key.match(delegateEventSplitter);
-        this.delegate(match[1], match[2], _.bind(method, this));
+        this.delegate(match[1], match[2], method.bind(this));
       }
       return this;
     },
@@ -1335,6 +1447,94 @@
 
   });
 
+  // Proxy Backbone class methods to Underscore functions, wrapping the model's
+  // `attributes` object or collection's `models` array behind the scenes.
+  //
+  // collection.filter(function(model) { return model.get('age') > 10 });
+  // collection.each(this.addView);
+  //
+  // `Function#apply` can be slow so we use the method's arg count, if we know it.
+  var addMethod = function(base, length, method, attribute) {
+    switch (length) {
+      case 1: return function() {
+        return base[method](this[attribute]);
+      };
+      case 2: return function(value) {
+        return base[method](this[attribute], value);
+      };
+      case 3: return function(iteratee, context) {
+        return base[method](this[attribute], cb(iteratee, this), context);
+      };
+      case 4: return function(iteratee, defaultVal, context) {
+        return base[method](this[attribute], cb(iteratee, this), defaultVal, context);
+      };
+      default: return function() {
+        var args = slice.call(arguments);
+        args.unshift(this[attribute]);
+        return base[method].apply(base, args);
+      };
+    }
+  };
+
+  var addUnderscoreMethods = function(Class, base, methods, attribute) {
+    _.each(methods, function(length, method) {
+      if (base[method]) Class.prototype[method] = addMethod(base, length, method, attribute);
+    });
+  };
+
+  // Support `collection.sortBy('attr')` and `collection.findWhere({id: 1})`.
+  var cb = function(iteratee, instance) {
+    if (_.isFunction(iteratee)) return iteratee;
+    if (_.isObject(iteratee) && !instance._isModel(iteratee)) return modelMatcher(iteratee);
+    if (_.isString(iteratee)) return function(model) { return model.get(iteratee); };
+    return iteratee;
+  };
+  var modelMatcher = function(attrs) {
+    var matcher = _.matches(attrs);
+    return function(model) {
+      return matcher(model.attributes);
+    };
+  };
+
+  // Underscore methods that we want to implement on the Collection.
+  // 90% of the core usefulness of Backbone Collections is actually implemented
+  // right here:
+  var collectionMethods = {forEach: 3, each: 3, map: 3, collect: 3, reduce: 0,
+    foldl: 0, inject: 0, reduceRight: 0, foldr: 0, find: 3, detect: 3, filter: 3,
+    select: 3, reject: 3, every: 3, all: 3, some: 3, any: 3, include: 3, includes: 3,
+    contains: 3, invoke: 0, max: 3, min: 3, toArray: 1, size: 1, first: 3,
+    head: 3, take: 3, initial: 3, rest: 3, tail: 3, drop: 3, last: 3,
+    without: 0, difference: 0, indexOf: 3, shuffle: 1, lastIndexOf: 3,
+    isEmpty: 1, chain: 1, sample: 3, partition: 3, groupBy: 3, countBy: 3,
+    sortBy: 3, indexBy: 3, findIndex: 3, findLastIndex: 3};
+
+
+  // Underscore methods that we want to implement on the Model, mapped to the
+  // number of arguments they take.
+  var modelMethods = {keys: 1, values: 1, pairs: 1, invert: 1, pick: 0,
+    omit: 0, chain: 1, isEmpty: 1};
+
+  // Mix in each Underscore method as a proxy to `Collection#models`.
+
+  _.each([
+    [Collection, collectionMethods, 'models'],
+    [Model, modelMethods, 'attributes']
+  ], function(config) {
+    var Base = config[0],
+        methods = config[1],
+        attribute = config[2];
+
+    Base.mixin = function(obj) {
+      var mappings = _.reduce(_.functions(obj), function(memo, name) {
+        memo[name] = 0;
+        return memo;
+      }, {});
+      addUnderscoreMethods(Base, obj, mappings, attribute);
+    };
+
+    addUnderscoreMethods(Base, _, methods, attribute);
+  });
+
   // Backbone.sync
   // -------------
 
@@ -1415,11 +1615,11 @@
 
   // Map from CRUD to HTTP for our default `Backbone.sync` implementation.
   var methodMap = {
-    'create': 'POST',
-    'update': 'PUT',
-    'patch':  'PATCH',
-    'delete': 'DELETE',
-    'read':   'GET'
+    create: 'POST',
+    update: 'PUT',
+    patch: 'PATCH',
+    delete: 'DELETE',
+    read: 'GET'
   };
 
   // Set the default implementation of `Backbone.ajax` to proxy through to `$`.
@@ -1435,6 +1635,7 @@
   // matched. Creating a new one sets its `routes` hash, if not set statically.
   var Router = Backbone.Router = function(options) {
     options || (options = {});
+    this.preinitialize.apply(this, arguments);
     if (options.routes) this.routes = options.routes;
     this._bindRoutes();
     this.initialize.apply(this, arguments);
@@ -1450,6 +1651,10 @@
   // Set up all inheritable **Backbone.Router** properties and methods.
   _.extend(Router.prototype, Events, {
 
+    // preinitialize is an empty function by default. You can override it with a function
+    // or object.  preinitialize will run before any instantiation logic is run in the Router.
+    preinitialize: function(){},
+
     // Initialize is an empty function by default. Override it with your own
     // initialization logic.
     initialize: function(){},
@@ -1507,11 +1712,11 @@
     // against the current location hash.
     _routeToRegExp: function(route) {
       route = route.replace(escapeRegExp, '\\$&')
-                   .replace(optionalParam, '(?:$1)?')
-                   .replace(namedParam, function(match, optional) {
-                     return optional ? match : '([^/?]+)';
-                   })
-                   .replace(splatParam, '([^?]*?)');
+        .replace(optionalParam, '(?:$1)?')
+        .replace(namedParam, function(match, optional) {
+          return optional ? match : '([^/?]+)';
+        })
+        .replace(splatParam, '([^?]*?)');
       return new RegExp('^' + route + '(?:\\?([\\s\\S]*))?$');
     },
 
@@ -1539,7 +1744,7 @@
   // falls back to polling.
   var History = Backbone.History = function() {
     this.handlers = [];
-    this.checkUrl = _.bind(this.checkUrl, this);
+    this.checkUrl = this.checkUrl.bind(this);
 
     // Ensure that `History` can be used outside of the browser.
     if (typeof window !== 'undefined') {
@@ -1576,8 +1781,8 @@
     // Does the pathname match the root?
     matchRoot: function() {
       var path = this.decodeFragment(this.location.pathname);
-      var root = path.slice(0, this.root.length - 1) + '/';
-      return root === this.root;
+      var rootPath = path.slice(0, this.root.length - 1) + '/';
+      return rootPath === this.root;
     },
 
     // Unicode characters in `location.pathname` are percent encoded so they're
@@ -1649,8 +1854,8 @@
         // If we've started off with a route from a `pushState`-enabled
         // browser, but we're currently in a browser that doesn't support it...
         if (!this._hasPushState && !this.atRoot()) {
-          var root = this.root.slice(0, -1) || '/';
-          this.location.replace(root + '#' + this.getPath());
+          var rootPath = this.root.slice(0, -1) || '/';
+          this.location.replace(rootPath + '#' + this.getPath());
           // Return immediately as browser will do redirect to new url
           return true;
 
@@ -1679,7 +1884,7 @@
       }
 
       // Add a cross-platform `addEventListener` shim for older browsers.
-      var addEventListener = window.addEventListener || function (eventName, listener) {
+      var addEventListener = window.addEventListener || function(eventName, listener) {
         return attachEvent('on' + eventName, listener);
       };
 
@@ -1700,7 +1905,7 @@
     // but possibly useful for unit testing Routers.
     stop: function() {
       // Add a cross-platform `removeEventListener` shim for older browsers.
-      var removeEventListener = window.removeEventListener || function (eventName, listener) {
+      var removeEventListener = window.removeEventListener || function(eventName, listener) {
         return detachEvent('on' + eventName, listener);
       };
 
@@ -1774,17 +1979,20 @@
       fragment = this.getFragment(fragment || '');
 
       // Don't include a trailing slash on the root.
-      var root = this.root;
+      var rootPath = this.root;
       if (fragment === '' || fragment.charAt(0) === '?') {
-        root = root.slice(0, -1) || '/';
+        rootPath = rootPath.slice(0, -1) || '/';
       }
-      var url = root + fragment;
+      var url = rootPath + fragment;
 
-      // Strip the hash and decode for matching.
-      fragment = this.decodeFragment(fragment.replace(pathStripper, ''));
+      // Strip the fragment of the query and hash for matching.
+      fragment = fragment.replace(pathStripper, '');
 
-      if (this.fragment === fragment) return;
-      this.fragment = fragment;
+      // Decode for matching.
+      var decodedFragment = this.decodeFragment(fragment);
+
+      if (this.fragment === decodedFragment) return;
+      this.fragment = decodedFragment;
 
       // If pushState is available, we use it to set the fragment as a real URL.
       if (this._usePushState) {
@@ -1794,7 +2002,7 @@
       // fragment to store history.
       } else if (this._wantsHashChange) {
         this._updateHash(this.location, fragment, options.replace);
-        if (this.iframe && (fragment !== this.getHash(this.iframe.contentWindow))) {
+        if (this.iframe && fragment !== this.getHash(this.iframe.contentWindow)) {
           var iWindow = this.iframe.contentWindow;
 
           // Opening and closing the iframe tricks IE7 and earlier to push a
@@ -1856,14 +2064,9 @@
     _.extend(child, parent, staticProps);
 
     // Set the prototype chain to inherit from `parent`, without calling
-    // `parent` constructor function.
-    var Surrogate = function(){ this.constructor = child; };
-    Surrogate.prototype = parent.prototype;
-    child.prototype = new Surrogate;
-
-    // Add prototype properties (instance properties) to the subclass,
-    // if supplied.
-    if (protoProps) _.extend(child.prototype, protoProps);
+    // `parent`'s constructor function and add the prototype properties.
+    child.prototype = _.create(parent.prototype, protoProps);
+    child.prototype.constructor = child;
 
     // Set a convenience property in case the parent's prototype is needed
     // later.
@@ -1890,5 +2093,4 @@
   };
 
   return Backbone;
-
-}));
+});