Tree sitter for Aiken

[rvcas]

We would like to have a complete tree-sitter grammar. There's been some work already on this front and it can be found here.

Important perspective: We want this exclusively for editor integrations. This is not meant to replace the parser in the compiler. So when building the grammar it's important to consider how things will look once tree-sitter is used for syntax highlighting. In general, always optimize the grammar for highlighting and navigation shortcuts.

No prior experience with tree-sitter is needed. Just read some docs and write tests. Existing tests can be found here.

If there's any confusion about Aiken's syntax as implemented by the parser in the compiler please refer to these locations:

• module entry point
• abstract syntax tree data types
• snapshot tests