Added yuck language support (for eww)

[Philipp-M]

Adds syntax highlighting support for yuck (DSL for eww). The parser should be complete now and closely follows the original lalrpop parser in eww.

[the-mikedavis]

Can this be covered by an lisp grammar we already include like clojure or scheme instead? Or is the syntax different enough that it needs its own parser?

[Philipp-M]

Well one thing that makes it indeed different (and more difficult at that, as it's a context-sensitive grammar), is that yuck includes a separate DSL that eww calls "simplexpr" (e.g. {time.date} or stuff inside string interpolation (which is a "simplexpr" as well). "simplexpr" seems to be a mix out of simple general expressions like binary/unary expressions, function calls and json data access.

[the-mikedavis]

Ah yeah, looks like there is string interpolation too which I don't think is supported in the existing lisps we have