radiant/texwindow: fix crash when assigning a tag, fix #146

radiant/texwindow: fix crash when assigning a tag, fix #146

Fix crash when assigning a tag, fix #146

Seems to be a bug introduced by @TimePath
in 0203ac024e9396ebc180d9721da40b90b7c33dc6 (Wrap more GTK)

It was probably a typo, this is the change for which a revert fixes the bug:

	-gboolean TextureBrowser_tagMoveHelper( ui::TreeModel model, ui::TreePath path, GtkTreeIter* iter, GSList** selected ){
	+gboolean TextureBrowser_tagMoveHelper( ui::TreeModel model, ui::TreePath path, GtkTreeIter iter, GSList** selected ){

The commit just re-add the pointer mark.