- Implement VT_BYREF | VT_BSTR marshalling.
- Add more integer types for marshaling and unmarshaling.
- Implement VT_BYREF | VT_BSTR unmarshaling.
- Don't allocate memory for TKIND_DISPATCH/TKIND_INTERFACE
  unmarshaling as it will be lost in the success case and interferes
  with the failure case.