EiffelStudio Homebrew package.

I've been told to do a PR here although I'm not sure how this would work for end users to get eiffelstudio without fidling with the homebrew configuration.

Thanks,
Manu
> Also it is not clear to me if there is a way to produce a 32-bit version of an executable on the latest versions of MacOS X.

It is possible, but don't worry about this. For most software, we only support building 32-bit on 32-bit CPUs. (E.g. people on early Core Duos, PPC users.)