WebComment: hierarchic notes support

* Notes can now be hierarchic: Note on Page 1, Fig. 3;
* Refactoring.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
WebComment: templates restructuring

* Notes are now displayed as a custom view for comments;
* Notes and Comments share a base template, which they customize.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
comments: notes porting

* Ported notes code from legacy to new structure

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
comments: textarea resize

* The comments' text area is now larger.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
WebComment: utils removal

* Removed webcomment_utils.py as it was moved to the new structure.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
comments: GUI howto-notes addition

* Included 'add comment' form tooltip which explains how to add notes.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
comments: notes warning

* Added a warning when viewing the notes, informing the user that this is a
summarized view of the record discussion.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>