Breaking changes

• This version only supports .NET Standard 2.1 (.NET Core 3.0) and up, because I started using nullable annotations and Span/Range constructs in the code. It's time to move to the future, folks!
• Base16 encoding/decoding methods have been moved to Base16.UpperCase and Base16.LowerCase respectively.
• Changed the static version of Base16.Decode() to receive a string as a parameter to avoid signature conflicts. (It's probably more practical this way)
• Removed string/byte[] overloads for Encode functions as they are redundant with .NET Core 3.0. Only Base16.Decode remained as a string due to function signature conflicts.
• Base32 is no longer whitespace tolerant.

New features

• New TryEncode/TryDecode interfaces for non-allocating encoding. Probably would be useful in massive number of encodings.
• Yubico's ModHex support for Base16.

Improvements

• More than 2x faster Base16 decoding
• Faster Base16 encoding
• More test coverage
• No more dependency to System.Runtime.Numerics
• Encoders now conform to common interfaces like IBaseEncoder, IBaseStreamEncoder, INonAllocatingBaseEncoder which make them pluggable, replacable with other implementations.
• Nullable reference annotations

Fixes

• Fix package license expression.
• Fix regression in Base16 optimizations.