edit-dialog: Commit sequence after poking at component

GcalEditDialog code pre-dates GcalEvent and apply changes directly
to the underlying ECalComponent. However, it doesn't commit the
sequence after doing so, which opens the door for doom.

Commit the component sequence after changing the recurrence data.

src/gui/gcal-edit-dialog.c

@@ -387,6 +387,7 @@ remove_recurrence_properties (GcalEvent *event)
 
   e_cal_component_set_recurid (comp, NULL);
   e_cal_component_set_rrules (comp, NULL);
+  e_cal_component_commit_sequence (comp);
 }
 
 static gchar*