GMP 5.1.0 — with new universal build strategy, works like a charm.

This my first commit, ever, to anything. So I wanted to do it right!

I think it should mostly? Be self explanatory. I tried to do some good inline documentation, but I got a little by the end. Anyway, I rewrote a whole new contraption that allows GMP detect hardware and to heavily optimize each architecture, then glue the two together. Passes all checks, works with autoenv, etc, etc. I've tested on 10.8, 10.6 and even 10.4 using the tigerbrew port. All seems to work fine. ...So not sure how this works exactly, ...any questions?

More to come!
~~~~ The Bathtub