Better MKV, OGM and WMV3 support

[Mr.Ash]

Hi Major,
How about to integrate better support for MKV, OGM and WMV3 files, like:

- OGM: mux, demux, extract, encode, etc. (like OGMtools)
- MKV: mux, demux, extract, encode, etc. (like MKVtoolnix)
- WMV3: playback (decode)

Would be great if you could include these functions in future releases of ffmpegX.