* thunar-vfs/thunar-vfs-monitor.c, thunar/thunar-tree-model.{c,h},

	  thunar/thunar-tree-view.c: Apply tree view pane improvements written
	  by Nick. It implements a GtkTreeModelFilter inside the tree model
	  and improves CPU performance when expanding folders in the tree
	  view. It also stops monitoring tree view folders when they are
	  closed. It improves thread safety in ThunarVfsMonitor and a few
	  other things. Should fix bug #4051.

(Old svn revision: 28917)