Rewrite it in Rust!

Gravity Core is getting a rewrite before I continue with this, and it won’t be able to be exported in HTML5 anymore. I’d like to be able to export HTML5, but I’m really not liking all the aspects of gdscript. I’d rather develop it in Rust, especially since this is mostly a fun project. When godot enables gdscript to work via WASM, HTML5 will come back.