Wasm Singlepass Experiment

This is an early-stage experimental project to build a single-pass wasm-function-to-machine-code translator.

It's currently built with dynasm and targets x86-64, however the function_body.rs/backend.rs split is likely to evolve towards a configuration point allowing other targets or even other assemblers to be supported.

It's a very early stage project, and a good one for learning how WebAssembly works at a low level, for learning assembly programming, or both! And we're happy to mentor. So welcome, and check out the issue tracker to see what's happening and how to get involved!