[FIX] iCal popup opening only once
[FIX] Conference overview display material manage
[FIX] Fix iCal export contrib display
[FIX] Improving search event by title
[FIX] Formatting / PEP8
[FIX] HTTP-API book a room: full rights for admins
[IMP] Get rid of the modal "room has avc" popup

Use a warningMessage div instead.
[REF] remove javascript: url and useless argument
[IMP] Moved pop-up left, removed capitals
[FIX] Missing quotes in html attr
[FIX] Unlink abstract from submitter on deletion

also do not raise in getConference() for deleted abstracts
[FIX] confUser.py & confLogin.py handling error

- Closes #1239
[FIX] RegForm duplicate email does not raise error

- Closes #1264
[FIX] Category material deletion exception
[FIX] RegForm register as admin redirection

- Closes #1277
[FIX] Infinite recursion in poster sessions
[FIX] Use correct slot schedule for new poster sessions
[FIX] Unlink categs from avatars on delete
[FIX] Download URL
[FIX] Migration script fails if no Vidyo plugin