Sender brackets notifications

The implementation of AdoptShapes brackets notifications with calls to BeginNotification and EndNotification. This causes the notifier to send a batched notification containing the separate notifications to receivers that have requested batched notifications.

  void TShapeList::AdoptShapes(TSequenceOf<MGraphic>& shapesToAdopt)
  {
      BeginNotification();
      TDeleterFor<TIteratorOver<MGraphic> > iterator = shapesToAdopt.CreateIterator();
      for (MGraphic* shape = iterator->First(); shape; shape = iterator->Next()) {
          AdoptShape(shape);
      }
      EndNotification();
  }