Changelog:
* Added two passes encoding mode, for both ffmpeg and mpeg2enc.
* Added new "unsharp" filter type, based on the y4munsharp tool.
* Now custom quant. matrices are also used with the ffmpeg encoder.
* The decoder tool can be specified.
* Audio pass-through is now enabled via the new -c flag.
* Tweaked a bit the mvcd output profile. It now uses its own "mvcd"
matrices and the audio bitrate is 128 instead of 224 kbps.
