 * Predicates loaded from file `user' should be treated as dynamic ones.
 * Document changes to clause_property/2 and the new hook prolog_event_hook/1.
 * Mixup of tracer over different break environments.
 * Document sources and tracer.
 * Better indication of choicepoints.

Multi-threaded applications:

	* Add debugging option to thread monitor
	* Add opening thread monitor from debugger
	* Avoid confusion on current location in threads
