blake2b 0.2.3

A dart implement of blake2b referenced from blacknet.

[0.0.1] - basic implement of blake2b

• just follow the blacknet's blake2b to implment it with dart.

[0.0.2] - wrap a Blake2bHash for common use

[0.1.0] - use Uint8List instead of Int8List

[0.1.2] - fix bug due to a wrong implement of array copy

[0.2.1] - null safety, remove flutter dependency

[0.2.2] - bugfix: bytes2long() overflow when in chrome see

[0.2.3] - feature: new constructor