references to avoid future issues.

- Removed default value assingment when default is equal to default(T)
- Added Benchmarks for most types and repeated/packed arrays
- Left PopsicleList's list fields uninitialized util needed
- Changed CodedInputStream's repated/packed reader
- Changed Enum writers to simply cast to int
- Changed the WriteEnum to use object rawValue that provides .ToString() if needed
- Should be fully on par with original library for performance, gaining 2x-3x in some cases