window proxy should delete its window during its destructor
change tortured GtkUI startup process into something just a little more sane, and remove "stopping" code since that belongs in a destructor
use new GtkUI design in ARDOUR_UI
delete the UI from main() to get full cleanup
change return type on ARDOUR::cleanup() since nobody cares what it returns
use AudioEngine destructor to do necessary stuff when shutting it down, and remove unused Config stuff in AudioEngine
remove debug output