Dev on hax

This chapter contains information about the internals of hax:

• Architecture: the components of hax and how they interact.
• Grammar of the supported Rust subset: the shape of the AST hax accepts, as eBNF.

The development setup, the structure of the repository, and the build commands are described in CONTRIBUTING.md; please read it before opening a pull request. Details on individual components are documented next to their code, in the README.md files of the respective directories.