0.8.13.40:

0.8.13.40:
	Un-32-bit-ify bignum.lisp in various ways, even trying to
	  do a quick fixup on the comments to remove 32-bit
	  assumptions.  Hasn't been tested with a real 64-bit
	  implementation, mind you.

	There's a *lot* of code for doing bignum digit divides
	  (anything prefixed with #!+32x16-divide);  no platform
	  currently uses it, but it might be worth twiddling with
	  the code to see if it's an improvement over the
	  VOP currently implementing %FLOOR.  Certainly it'd be
	  nice to move more code into Lisp-land.