NbtkTable: Use clutter_container_remove_actor when emptying the table
NbtkTable: Use clutter_container_remove_actor when emptying the table

This change means we do not leak the ClutterChildMeta that gets created on
clutter_container_add_actor.

pwithnall/mx,pwithnall/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,clutter-project/mx,jonnylamb/mx,clutter-project/mx