Better support for handling 'object' values in tuples (where the type is not know at compile time)

- Fixed the generic Pack<Object>(...), Create<Object>() and  Concat<Object>(...) methods
- Added non-generic PackBoxed(object), ConcatBoxed(..) and BatchPackBoxed(...) methods
- Renamed DeserializeObject to DeserializeBoxed to match
- Renamed Create(IEnumerable<object>) into FromEnumerable(...) to fix overload resolution ambiguity by the compiler.
- Renamed Create(object[], int, int) into FromArray(...) for the same reason.
- Added more unit tests