Improve performance. Add benchmark and serialization projects.

[aalmada]

Main features:

• Changes Equals() and GetHashCode() to only compare Value.
• Adds TryFromName() and TryFromValue() methods. These allow searching without exceptions thrown, improving considerably performance.
• Adds a ignoreCase parameter to FromName() and TryFromName(). The default value is false for better performance.
• Adds inline documentation.
• Adds benchmarking project for performance evaluation of SmartEnum common operations. Also measures performance when using enum, Enums.NET and Constant.
• Adds support for SmartEnum (de)serialization using Json.NET, Utf8Json, MessagePack-CSharp and protobuf-net.