TODO

 - Rework internal GcalWindow working
 - Add disable/enable of views
 - Rework GcalViews as grid only (WeekView, MonthView, YearView)
 - Rework GcalViews to implement the new API (remove every "New API" comment)
 - Make GcalTimeSelector an entry
 - Properly fix timezone handling
 - Rethink signals from GcalManager
 - Order events chronologically in views
 - Change ordering of events in all-day views (use a custom ordering)
 - Add different triggers for hiding the sources view.
 - Check for the real need of adding timezone, and check everywhere
 - Connect all dconf options to the program
 - Check the real need of a caching GcalManager

Design stuff

 - How to handle timezones?
 - How should a Single Day view look like?
 - Need mockups for:
   * Day view
   * Agenda view
   *
 - What to do when there's no host set in the event.

Wish-list

 - Make GcalEventWidget a composite widget
   * Turn into a GtkGrid subclass
   * Remove all the custom drawing madness
 - Add resize-by-handlers capabilities to GcalEventWidget