dav_events: presort events by date, number to improve performance of datatable javascript output

dav_events/views/events.py

@@ -55,7 +55,7 @@ class EventListView(generic.ListView):
 
             qs = self.model.objects.filter(filter)
 
-        return qs
+        return qs.order_by('-first_day', 'number')
 
     def get_context_data(self, **kwargs):
         context = super(EventListView, self).get_context_data(**kwargs)