[FIX] Deletion of VS triggered

- When a Contribution or SessionSlot is deleted
[FIX] Merge API keys

More recent one is preserved if both users had one
[FIX] categ manager email when adding egroup
[FIX] Add canModify to SessionSlot
[FIX] HTTP API canModify in CSBookings
[FIX] Social events check selected
[FIX] RegForm: Ensure no unicode is stored in db
[MIN] Some PEP8 love

 * OmeGak
[IMP] Timetable: Weekly view
[NEW] Icomoon icon: small circle
[IMP] week timetable style
[IMP] Various improvements in the week TT
[MIN] Remove duplicate icomoon icon