Review request for batteries#1333

Stream: batteries

[François G. Dorais]

I would like someone to review batteries#1333 : add character casing lemmas. This PR adds lemmas for reasoning about ASCII character casing functions (Char.isAlpha, Char.isLower, Char.isUpper, Char.toLower, Char.toUpper). There are a lot of lemmas but I expect this to be a straightforward review.

This is needed because I cannot merge my own PR without review and it will greatly help two user PRs about case-insensitive comparison.

[François G. Dorais]

Completed. Thanks!