v2.0.0

• Changed password hashing to always use a random salt.
• Changed salts to use an opaque Salt type for verified whole-byte salts.
• Added derive_encryption_key for key derivation where use of a stored salt is required.
• Corrected the memory default for Argon2i from 12,228 bytes to 12,288 bytes.
• Renamed argus.Hashes to argus.HashOutput for clarity.