Pull request/lua51

* Move `Library/Formula/lua.rb` to `Library/Formula/lua51.rb, because it uses the (not counting bugfix releases) 7 year old lua-5.1, 
* Import `lua52.rb` from `homebrew/versions` tap repository.
* Add an Alias so that `brew install lua` picks up the current (not counting bugfix releases) 2 year old lua-5.2.

I've also drastically simplified the formulae by moving the patches to gists after they grew substantially when adding the changes to mangle installation paths some more to enable parallel installation of lua51.rb and lua52.rb.

And finally, while rewriting the Formulae, I updated the options to work with `build.with?` instead of `build.include?`.

( Ref: https://github.com/mxcl/homebrew/issues/20659 and https://github.com/mxcl/homebrew/pull/20657 )