Use `unAlpha` instead of `fromLetter`. Same thing.
Revert "Add Letter type that doesn't parse from punctuation."

This reverts commit d16bd18ec6092a2fa49dab98115289f15aad5ca3.

Redundant with Alpha.
JSON parsing instance that read strings from numbers.
Make 'coral' accept integers or letters.
Draw coral shading below grid lines.
Rename `countnumbers` to `meanderingnumbers`.
Update changelog.
Bump version number, release 0.1.0.4.