Implemented timerange for mdplayer and use of it in widget Segment: if enable (option is use_timerange) when clicking a segment user can only read the video on current segment + adapted other widgets that need to detect segment to be able to use this option if it is enable so that segment detection is smoother + adjusted API testing form on iframetesting to use the correct api (form is still hidden by default)

// Responsive utilities

//
// More easily include all the states for responsive-utilities.less.
.responsive-visibility() {
  display: block !important;
  table&  { display: table; }
  tr&     { display: table-row !important; }
  th&,
  td&     { display: table-cell !important; }
}

.responsive-invisibility() {
  display: none !important;
}