0.6.8.21:

0.6.8.21:
	rewrote DEBUG-PROMPT to be less confusing when ILISP and SBCL
		fight and end up 8+ levels deep in the debugger, then
		relented and gave some advance warning of prompt change
	deleted unsupported *DEBUG-PROMPT*
	We don't really need an END-OF-THE-WORLD restart. The point was
		to make sure a naive user can get out with Ctrl-C. So
		mention (SB-EXT:QUIT) in entering-the-debugger message.
	reduced choice-of-output-stream chaos in debugger