Add tests related to error handling.

Traditional British long count is available for systems.

Only largest millia should remove prefix when group is 001.

Make short millia parse and stringify correctly.

Use special millions prefix only when millia is less than one.

Add namespace for short/long count. Also manage conversion configs and defaults.

Enable all tests in project.

Ensure exponents are normalized properly.

Make group management more readable.

Address errors with gapped groups.

Ensure digits parse correctly when there are gaps.

Make code more cleaner when parsing.

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