event: add recurrence property

Earlier, an event had no recurrence property. Hence, the event's
recurrence pattern etc. could not be analysed, and as a result
could not be changed by the user. gnome-calendar just displayed
all the recurrences of a recurring event but had no 'readable'
knowledge regarding the characteristics of those recurrences.

This patch adds the recurrence property, which is basically
a GcalRecurrence structure linked to the event.

https://bugzilla.gnome.org/show_bug.cgi?id=782755

src/gcal-event.h

@@ -19,6 +19,8 @@
 #ifndef GCAL_EVENT_H
 #define GCAL_EVENT_H
 
+#include "gcal-recurrence.h"
+
 #include <glib-object.h>
 #include <gtk/gtk.h>
 #include <libecal/libecal.h>
@@ -122,6 +124,12 @@ gint                 gcal_event_compare_with_current             (GcalEvent
                                                                   GcalEvent          *event2,
                                                                   time_t             *current_time);
 
+void                 gcal_event_set_recurrence                   (GcalEvent          *event,
+                                                                  GcalRecurrence     *recur);
+
+GcalRecurrence*      gcal_event_get_recurrence                   (GcalEvent          *self);
+
+
 G_END_DECLS
 
 #endif /* GCAL_EVENT_H */