Add VS2012 support.
* We use the same project files as VS2010 which makes things easier to maintain.
* We don't use any MFC hack to reduce the binaries' size. We use the _AFX_NO_MFC_CONTROLS_IN_DIALOGS define for the standalone filters which has the same effect and it's cleaner. MPC-HC itself is a little bigger uncompressed, but its compressed size is the same.