Address errors with gapped groups.

Ensure digits parse correctly when there are gaps.

Include parse and stringify functions for American short-count locale.

Ordinals have been implemented in both English and German (tho I'm not
sure how to check correctness of German number names and ordinals).

Also, refactored code to have common rules for a language, and special
rules for each variant (in the future, French will have this structure
handy).

Make sure cases from chongo are accounted for.

Add files from pridepack.