Gordon-Sau

The TypeClassLang is currently defined in `typeclass/typing/tcexpScript.sml` in the `typeclass` branch. It is basically extending the original `tcexp` with type annotations (as `option` types). The `Case` are converted into `NestedCase`....

`Class` and `Instance` declarations are included in the AST, and the types are expanded with constraints. There are incremental updates in the parser. ### Design Decision - It is decided...