0.8.13.3:

0.8.13.3:
	Improve BIGNUM-GCD ever so slightly
	... BIGNUM-INDEX isn't actually usefully INDEX, because we
		require the ability to index individual bits.  Divide
		the type by 32, then.
	... rearrange bignum.lisp slightly to declare types of functions
		before their use.  (Aside: I'm not sure why I need the
		type declaration, given that the final compiler can
		derive the type fine.  Maybe the cross-compiler is
		lobotomized in some significant way here?)