[Feature Request] Add Support for BLAKE2

[tERyceNzAchE]

Add support for BLAKE2 for compatibility with other programs (DirHash, b2sum, RapidCRC, etc.)

1. Add support for BLAKE2b (256 bit) with the file extension .blake2
2. Add support for BLAKE2sp (256 bit) with the file extension .blake2sp

Other BLAKE2 variants are not as commonly used and can be omitted.

[KrasnayaPloshchad]

Try XKCP for the implementation