0.7.12.39:

0.7.12.39:
	Refactor some of the type system:
	... new TYPE-CLASS: NEGATION, for representation of (NOT FOO)
	... in TYPEP/CTYPEP/SOURCE-TRANSFORM-TYPEP, too
	Also add a few smarts to the existing type system
	... give up slightly less often in INTERSECTION-COMPLEX-UNION2
		and UNION-COMPLEX-INTERSECTION2
	... now that we have a distinct NEGATION class, it's possible to
		write sensible UNION and INTERSECTION methods for those,
		too
	Fixes:  (SUBTYPEP T (OR REAL (NOT REAL))),
		(SUBTYPEP T (OR KEYWORD (NOT KEYWORD)))