2006-09-26  Kristian Rietveld  <kris@imendio.com>

	* gtk/gtktreemodelfilter.c (gtk_tree_model_filter_init),
	(gtk_tree_model_filter_finalize), (gtk_tree_model_filter_row_deleted),
	(gtk_tree_model_filter_new): unref the virtual root path once that
	node (or one if its ancestors) is deleted, set virtual_root_deleted
	so we only unref it once.