Summary

This PR contains the changes needed to rewrite this crate in order to provide a better experience during the build process.

What has been done

Where before code generation was done through a test ran with cargo test it is now done in a separate crate using a build.rs script.
definitions for tokens etc. have been moved to a separate crate.
tests and usages of generated code have been rewritten in order to adapt to the changes
DEVELOPMENT.md has been rewritten in order to provide better insight into this repositories' structure and how to contribute within its confines.