Some preparation work for doing async. activation. This amounts
	to another pass cleaning up the legendary "state machine" as well
	as some other cleanups in the async. activation code.

	* libnautilus-extensions/nautilus-bonobo-extensions.h:
	* libnautilus-extensions/nautilus-bonobo-extensions.c:
	(oaf_activation_callback), (nautilus_bonobo_activate_from_id),
	(nautilus_bonobo_activate_cancel): Fix interface of activation to
	be cleaner. Also handle case where callback is called right away.

	Add queuing to NautilusView so that all incoming CORBA calls are
	dispatched at idle time. This can fix some otherwise-difficult
	re-entrancy problems. The widget destroy call can still come in at
	any time though. Also this same fix may be needed for the
	NautilusViewFrame side.

	* libnautilus/nautilus-view.h:
	* libnautilus/nautilus-view.c: (execute_queued_calls): Function
	to dequeue and execute calls.
	(dequeue_calls_at_idle): Cover to call it at idle time.
	(di...