* * debug.scm: *Warning* This feature is a bit premature. I add

*	* debug.scm: *Warning* This feature is a bit premature.  I add
	it anyway because 1. it is very useful, and, 2. you can start
	making it less premature by complaining to me and by modifying
	the source! :-)
	(trace): Given one or more procedure objects, trace each one.
	Given no arguments, show all traced procedures.
	(untrace): Given one or more procedure objects, untrace each one.
	Given no arguments, untrace all traced procedures.  The tracing in
	Guile have an advantage to most other systems: We don't create new
	procedure objects, but mark the procedure objects themselves.
	This means that also anonymous and internal procedures can be
	traced.

	* boot-9.scm (error-catching-loop): Added handling of apply-frame
	and exit-frame exceptions.

*	* boot-9.scm (assert-repl-prompt, the-prompt-string): Removed.
	(set-repl-prompt!): Setter for repl prompt.
	(scm-style-repl): If prompt is #f, don't prompt; if prompt is a
	string, display it; if prompt is a thunk, call it and display its
	result; otherwise display "> ".
	(Change suggested by Roland Orre <orre@nada.kth.se>.)