nimrod-lang: New and improved formulas

This pull request attempts to improve Homebrew's support for the Nimrod language by supplying two new and improved formulas. The explanation for the changes are in the commits themselves, and I'd also be happy to answer any questions about this here.
I think the best solution here would be to work with upstream to ensure we support the same thing. We don't want to be trying to support platforms that upstream does not; it's recipe for users and upstream getting annoyed when there are bugs.