brewkit.rb changes ENV destructively, so lets not do that everytime a formula
is required. Now it's possible for other tools to require a formula
description without worrying about side-effects.
Also removed xmlrpc-c dep, by coercing cmake into using its own xmlrpc
copy. It statically linked xmlrpc before anyway, so it's better for our
users not to have this crappy dependency.
Still completely in the dark about how cmake can possibly need an
xmlrpc library!
Moved Forumla and Cellar/homebrew into Library.
This way the homebrew core files are more sensibly placed, Cellar is
more internally consistent and only generated. And Homebrew is ready for
use straight out of the tarball.
