hybrid-array: is the `ByteArray` type alias useful?

[tarcieri]

hybrid-array currently contains a ByteArray type alias which maps to Array<u8, U>.

I'm wondering if it's actually useful or perhaps less clear than just using Array<u8, U>.

It's been used in a few places in the WIP crypto-common/block-buffer/cipher/digest prereleases.

[newpavlov]

Personally, I prefer Array<u8, U>, but I am fine with ByteArray<U>.

They both have exactly the same length and the latter is slightly easier to type and read, but it could be slightly confusing since Rust often substitutes type aliases, e.g. compilation error messages will contain Array<u8, U>, despite code seemingly only using ByteArray<U>.