0.8.5.34

0.8.5.34
	Add *INVOKE-DEBUGGER-HOOK*, which works basically like the
	ANSI *DEBUGGER-HOOK* but isn't bound to NIL in calls to
	BREAK, so can be used to trap _all_ debugger entry, not just
	some of it.  Useful for anyone who wants to completely remove
	the debugger, or supplant it with something else.

	Based on a patch from David Lichteblau, but this one only has
	a single function instead of a list in the hook.