Update to new Forge version & new mappings.
Created by: Koward
This is a pretty big PR that reformats code and update to new Forge & MCP mappings. I have trouble to test it right now as my laptop don't have enough memory and exceeds the limit when baking models, but I'll do it soon. EDIT : Done. Seems to be OK. I'll include some reformatting & small simplifications done at the same time.