This eliminates the (optional) libresample dependency, which will clean up
building and eliminate the goofy 5k DLL. It's also faster.
This doesn't implement "HighQuality". That would involve changing L from
8 to 16. I might implement that in the future, but it sounds decent to me. (It's
a little tricky, since PolyphaseFilter::RunPolyphaseFilter needs L to be
a constant for speed.)