Added duration property to events

Calendar/CalendarEvent.py

@@ -3,6 +3,7 @@ class CalendarEvent (object):
     def __init__ (self):
         self.begin_datetime = None
         self.end_datetime = None
+        self.duration = None
         self.all_day = None
 
         self.title = None

Calendar/IcalEvents.py

@@ -45,6 +45,7 @@ class IcalEvents(CalendarInterface):
                     cal_event.fetch_datetime = datetime.now()
                     cal_event.begin_datetime = event.begin.datetime
                     cal_event.end_datetime = event.end.datetime
+                    cal_event.duration = event.duration
                     cal_event.title = event.name
                     cal_event.description = event.description
                     cal_event.location = event.location