view iface: remove unused will_add_event

ECalDataModelSubscriber interface notify each view only about the events
beloging to the subscribed range so there's no need of checking if the
event widget will be added.
The safety check of not adding the same widget twice its stil being made
on each GtkContainer::add implementation.

src/gcal-view.h

@@ -71,9 +71,6 @@ struct _GcalViewIface
   gboolean        (*draw_event)                         (GcalView *view, icaltimetype *start_date, icaltimetype *end_date);
   GtkWidget*      (*get_by_uuid)                        (GcalView *view, const gchar *uuid);
   void            (*clear)                              (GcalView *view);
-
-  /* Newer API */
-  gboolean        (*will_add_event)                     (GcalView *view, GcalEventWidget *event);
 };
 
 GType         gcal_view_get_type                      (void);
@@ -114,9 +111,6 @@ GtkWidget*    gcal_view_get_by_uuid                   (GcalView     *view,
 
 void          gcal_view_clear                         (GcalView     *view);
 
-gboolean      gcal_view_will_add_event                (GcalView     *view,
-						       GcalEventWidget *event);
-
 G_END_DECLS
 
 #endif /* __GCAL_MONTH_VIEW_H__ */