clean up the VS project files a little, including taking out a definition of _WIN32_WINNT to -0x400 (yes, minus, I have no idea how that got in there)
make sending the new expanded wavpack_codec_private_data conditional on it actually being required (i.e., greater than 6 channels, non-standard channel masks, or 32-bit integer audio) - this way, in the vast majority of cases we just send the 2-byte version like before (which is more likely to be compatible with other software out there that might be using this)