vf2h and minor vh2f tweaks

This is enough to make Fat Princess no longer crash when you kill things.  Still only works in Gladiate and Mess About modes.

Passes vf2h -> vh2f tests, but doesn't pass some bitwise tests (like I think the -INFINITY one.)  Even so, fairly close.  Also added links to gists with more info on ryg's conversions.

Also corrects prefix handling based on tests.  Although, something is funny with the D prefix on vf2h...

-[Unknown]