BSE: remove unused bse_item_undo_depth, bse_item_redo_depth
BSE: remove unused bse_item_undo_depth, bse_item_redo_depth

tim-janik/beast,swesterfeld/beast,tim-janik/beast,swesterfeld/beast,swesterfeld/beast,GNOME/beast,GNOME/beast,tim-janik/beast,swesterfeld/beast,tim-janik/beast,tim-janik/beast,GNOME/beast,GNOME/beast,swesterfeld/beast,GNOME/beast,tim-janik/beast,GNOME/beast,swesterfeld/beast,GNOME/beast,tim-janik/beast,swesterfeld/beast