coplanar/calendar: Add a missing semicolon
coplanar/model: Add post fetch filtering
coplanar/calendar: Allow passing a filter to the events query
GV View/Event: Allow filtering on state, eventType and location
GV/UI: Add links to some room calendars
coplanar/model: Add validation functions for date and time
GV/model: Validate the start and end of plannables as date
GV/model: Remove useless validation on Hostel objects

The "start" attribute is already validated in the parent class.
GV/model: Validate the start of event program as time
coplanar/app: Add a template env function to login the user
GV/UI: Add a menu entry to login when one is Anonymous