Improve handling of invalid FontConfig data.

Fuzz test roundtrip conversions between C & Haskell datastructures!

Properly handle ambiguity in empty char/lang sets.

fuzz-test MessagePack implementations.

Constrain public API.

Implement utils for loading queried fonts.

Integrate fontsets with Haskell Stylist.

Implement Stylist traits for FontConfig patterns!

Improve memory safety & error checks.

Expose font weight adjustments & correct current-config refcount.

Finish initial redraft

Write init/finalize & pattern language bindings, haskell-side!

Encode & decode charsets on C side (fix Haskell side)

Datamodel FontConfig in Haskell.