Revision 14

	* Thuban/UI/tree.py (myTreeCtrlPanel.__init__): New inst var
	changing_selection to avoid recursive selection events when
	modifying the selection in response to a selection event.
	(myTreeCtrlPanel.normalize_selection): Set the new inst var when
	changing the tree's selection.
	(myTreeCtrlPanel.OnSelChanged): Only normalize the selection when
	we're not being called indirectly from normalize_selection.