It's planned. The reason it isn't already open-source, is that it's a wretched, bloody mess that no-one can comprehend without spending two years on it. Saffith is slaving over it, to make it a big nicer for an O-S project, with some degree of success. No-one can tell you how long it will be, before it's ready, so there's that to bear in mind.

The codebase is C++, and relies on Allegro 4 (so you might want to read up on that, if you are interested in contributing at some point), if any of that matters to you.