version 1.0.0

Changes since 0.3.8:

• Add Hash::from_hex() and implement FromStr for Hash.
• Implement Display for Hash, equivalent to Hash::to_hex().
• Implement PartialEq<[u8]> for Hash, using constant_time_eq.
• Change derive_key() to return a 32-byte array. As with hash() and keyed_hash(), callers who want a non-default output length can use Hasher::finalize_xof().
• Replace Hasher::update_with_join() with Hasher::update_rayon(). The former was excessively generic, and the Join trait leaked implementation details. As part of this change, the Join trait is no longer public.
• Upgraded arrayvec to 0.7.0, which uses const generics. This bumps the minimum supported Rust compiler version to 1.51.
• Gate the digest and crypto-mac trait implementations behind an unstable feature, "traits-preview". As part of this change upgrade crypto-mac to 0.11.0.