0.8alpha.0.14

0.8alpha.0.14
	Merge thread-gc-branch.

	Summary: move time-to-gc-p logic entirely into C.  Delete a
	lot of Lisp stuff no longer necessary.  Make SUB-GC
	thread-safe or at least thread-tolerant.  Some hooks and
	variables that were previously available but not apparently
	used for much are now no longer present.