C5 3.0.0-rc

C5 3.0 of 2021-12-22: - C5 now targets .NET Standard 2.0 and .NET 6.0. - Documentation is autogenerated on build and published to <https://c5.azurewebsites.net/>. - Strong name removed. - Memory safe optimizer removed as they are no longer needed for Unity development. - `Rec<T1, T2, ...>` type removed as was an exact copy of `ValueTuple<T1, T2, ...>`. - Breaking change: All `public readonly` are now properties. - Breaking change: `EventTypeEnum` is now `EventType`. - Breaking change: custom `KeyValuePair<K, V>` has been replaced by the standard `System.Collections.Generic.KeyValue<TKey, TValue>` for better compatability. - Deprecation warning: As per [BinaryFormatter security guide](https://docs.microsoft.com/en-us/dotnet/standard/serialization/binaryformatter-security-guide), binary deserialization present high security risk. For this reason the `[Serializable]` attribute will be removed from the entire library in the next release.