Currently, all the Wine msxml versions point to msxml3. So if there is a native override for msxml3, all the other versions will cease to work, since they expect our msxml3. This change moves the actual implementation to winexml.dll, so that all versions will function even if msxml3 is native.
Suggestions welcome. I wasn't quite sure what should end up where, so I took the approach of only moving the absolutely necessary components to winexml.