Made simple-add event work.

Fixed GcalEventOverlay handling of dates.
Added initial code and methods to handle adding events to GcalManager.
Fixed in GcalMonthView handling of dates passed to event-creation.
Fixed gcal-utils sources for gcc warning.
Fixed calling order in GcalWindow.

src/gcal-utils.c

@@ -90,7 +90,7 @@ gcal_get_group_name (const gchar *base_uri)
 }
 
 icaltimetype*
-gcal_dup_icaltime (icaltimetype *date)
+gcal_dup_icaltime (const icaltimetype *date)
 {
   icaltimetype *new_date;