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
Hm, does this mean that nothing is linked into the standard paths (e.g. `bin`, etc.)? Is there a way to install in something more resembling a standard Unix layout, or to install a launcher symlink in `bin`?