Revision 37

	* Thuban/UI/mainwindow.py (MainWindow.current_layer):
	(MainWindow.has_selected_layer): Simply call the appropriate
	interactor method

	* Thuban/UI/mainwindow.py (MainWindow.__init__):
	(MainWindow.LayerShowTable):
	(MainWindow.identify_view_on_demand): Store the interactor in an
	instvar and use that reference instead of going through main.app

	* Thuban/UI/mainwindow.py (MainWindow.ShowSessionTree):
	* Thuban/UI/application.py (ThubanApplication.OnInit):
	* Thuban/UI/main.py (main): Create the session tree view in main
	with the new mainwindow method ShowSessionTree and not directly
	the application's OnInit method