appmenu: Remove "New Event" entry

The "New Event" menu item is confusing and misleading, since
it is contextless item that has a context-aware action. The
result varies depending on which view you are, but this is in
no way communicated.

So just remove that, and all the GcalWindow API that is not
used anymore altogether.

src/gcal-application.c

@@ -59,10 +59,6 @@ struct _GcalApplication
   GcalClock          *clock;
 };
 
-static void     gcal_application_create_new_event     (GSimpleAction           *new_event,
-                                                       GVariant                *parameter,
-                                                       gpointer                 app);
-
 static void     gcal_application_launch_search        (GSimpleAction           *search,
                                                        GVariant                *parameter,
                                                        gpointer                 app);
@@ -113,7 +109,6 @@ static GOptionEntry gcal_application_goptions[] = {
 };
 
 static const GActionEntry gcal_app_entries[] = {
-  { "new",    gcal_application_create_new_event },
   { "sync",   gcal_application_sync },
   { "search", gcal_application_launch_search },
   { "about",  gcal_application_show_about },
@@ -555,15 +550,6 @@ gcal_application_init (GcalApplication *self)
   self->search_provider = gcal_shell_search_provider_new (self->manager);
 }
 
-static void
-gcal_application_create_new_event (GSimpleAction *new_event,
-                                   GVariant      *parameter,
-                                   gpointer       app)
-{
-  GcalApplication *self = GCAL_APPLICATION (app);
-  gcal_window_new_event (GCAL_WINDOW (self->window));
-}
-
 static void
 gcal_application_sync (GSimpleAction *sync,
                        GVariant      *parameter,