A JIT compiler for Rust

This project is an attempted rewrite of Bebbington's jit.rs and will look very, very similar to it for a while. As that repo has not been touched in a long time a lot of the Rust is out-of-date so a lot of things are probably in error by today's standards

Feel free to help out in any way possible! That includes advice, PRs, or a simple 'good luck' tweeted to me @_mttyng