Finish refactoring the toolbar to use only actions

Finish refactoring the toolbar to use only actions

Finally the trash, which was the last item that
needed to be implemented as an action, is an
action, a KatzeArrayAction to be exact.

This simplifies more code and also makes Window
and RecentlyVisited generically implementable.

Incidentally this change also fixes a bug where
the browser tried to add a new tab when the last
one was closed, even while destroying itself.

Furthermore sokoke_image_menu_item_ellipsized
and sokoke_widget_popup were promoted to Katze.
We're still keeping the old functions for now.