removed

- Update the ToolBarManager when MToolBar children change: add,
remove, move.
- Reduce the number or add/remove/move events when a ToolBarManager is
reconciled to model
- Reconcile  visibility of existing items from ToolBarManager to model

Change-Id: I21ee015b1cdbf226ac5eba6d729de5365b70cc32
Signed-off-by: Rolf Theunissen <rolf.theunissen@gmail.com>