ReservationOccurrence bulk creation and cleanup
Post rebase fixes
Added overlapping helpers to datetime utils
Overlap methods added to ReservationOccurrence
Fixed ReservationOccurrence bulk creation with TZ
Generalized BarList2Dictionary helper

* Created group_list method
* Removed unnecessary class
* Renamed iterators.py
Prevent overlap checks between different rooms
Moved iterdays to indico.util.date_time with rrule
Refactored Bars and removed unncessary methods
Fixed photo_id reference in RoomMiniDetails tpl
Adapted RoomBookingCalendar to new backend
Room BookingForm populate form from request
Adapted view of BookForm page to new backend

* Adapted template
* Removed unused endpoints and methods
Booking form fields render with WTForms
Post-WIP fixes