Added MD5 checksum. It's faulty right now, but it's also 3:20 AM, so... commit and sleep.
Ahahah, it was little endian! All my problems. Will write unit test next.
Wrote unit tests for MD5, and made a (very terrible) framework for tests in general.

I can write test functions, but I'm not sure how to string them all together in a framework. Work on that.