* gladeui/glade-command.c: queue selection changes when widgets are added, this
	  avoids synchrounously poking the model when the selection changes various times
	  in a command sequence such as changing a menu item's type.

	* gladeui/glade-base-editor.c: Dont call glade_command_create/delete() directly
	  in change-type, keep delegating this work to build-child/delete-child signals.

	* gladeui/glade-widget.[ch]: Added glade_widget_is_ancestor()

	* gladeui/glade-utils.c: Change glade_util_find_iter_by_widget() to use
	  glade_widget_is_ancestor() and speed up searches a little this way.