Add features and limitations to the project.

Also update the types to be stricter.

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 word positive when making negative a negative number.

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.

Ensure exponents are normalized properly.

Use bigint for place values to be more adaptable with longer inputs.

Put functions with different purposes into their own files.