add parameter to filter session and note by updated date. Add pagination on sessions and notes. add read only endpoint at root level to list notes
## install seqdiag
```bash
$ pip install seqdiag
```
## resources
- [full documentation of seqdiag](http://blockdiag.com/en/seqdiag/introduction.html)
## examples:
### Generate png with white background
```bash
$ seqdiag -f <path to>/DejaVuSansMono.ttf metacategory_editor.diag --no-transparency
```