7bbdd9b2af Export all hash types (Tobin C. Harding)
Pull request description:
During the 0.30.0 release we removed the re-exports of hash types. This upset some folk and since the aim of our re-exports is not exactly clean as well as the fact that the public API surface is not yet fixed just re-export all the hash types at the crate root again.
This is #1792 but does not use a wildcard and also grabs the other hashes that we recently moved.
ACKs for top commit:
apoelstra:
ACK 7bbdd9b2af
sanket1729:
ACK 7bbdd9b2af
Tree-SHA512: addfb617fae2fce12eb9d198ffeb1b0c99792dfd757222c21c62bd4b408432de5dc93c42da7d886b43c29b2c34bd318573e813f567a29080fc264ee7beba0f70