Fix CodeDOM serializer generator does not reset some internal state.

CodeDomContext.ResetCore forgot to clear cached FieldInfo/MethodInfo for non-public member [de]serialization, so extra fields are generated when multiple serializer generation at a time.
This fix just add Clear() invocation on ResetCore.
Re-generated genreated serializer with fixed CodeDOM serializer.
Fix unnecessary reflection access for collection typed property.

From simple missing not operator, simple get accessor invocation was replaced with reflection. It hurts performance.
This fix just add not operator.
Improve mpu --reference option.

This commit adds short option for --reference because it is effectively required option. In addition, ./MsgPack.dll is included in default now because this assembly is always required.
Improve path distinction.

This commit prevents conflicts caused by naive path comparison with path canonicalization and case-insensitive comparison for Windows.
Fix lambda expression cannot be used in the mpu.exe's target source code in Mono.

This commit adds complier options to resolve it.