Improve media player engine

This task includes next improvements into player audio/video engine work: 1. Improve work of "audio tracks switching" during video playback between internal audio tracks and external AC3 tracks. This feature has been implemented in first version of player engine, but worked with some bugs. We did not check this feature work in second version of engine, if this feature was commented in second version then need to return it back and fix all bugs. Switching between audio tracks should work more smoothly then it worked in first version. Also if video has a few internal audio tracks then engine selects to play the longest track between available that sometimes is NOT default track. This logic need to check and rewrite. 2. Add support playback multi-video files like m2ts with ability to switch between videos. For now during playback m2ts files player engine selects the longest video stream and longest audio stream and so we have sometimes played incorrect default video with audio from another video. This feature connected to p.1. 3. Player engine supports internal video subtiles in first version of engine but with some bugs that need to fix. We did not check this feature work in second version of engine, if this feature was commented in second version of engine then need to return it back and fix all bugs. Also need to add support of external subtitles. Player engine should support all internal subtitles that FFmpeg supports ([login to view URL]). Player engine should support all external subtitles that MPC-HC supports (*.srt, *.sub, *.ssa, *.ass, *.smi, *.psb, *.txt, *.idx, *.usf, *.xss). 4. Add support codecs installed in system and Windows Media codecs. 5. Player engine uses ffmpeg 1.1.3 for now. Player engine should be upgraded to use last available FFmpeg 2.1.1. Player engine should play all files that ffplay 2.1.1 plays. 6. Add support CD/DVD playback to player engine. Coder can ask for additional bonus $500 for implementing this feature if implementing this feature will take more time then coder expected. This task includes ONLY fixes to player engine work and does NOT include UI fixes. One note to p.5. If you start this project in begin of January then please use the latest FFmpeg version available at this time (probably will be available more newest FFmpeg version then 2.1.1). We use Visual C++ 2010 to compile CherryPlayer UI and player engine dlls should be compilled correct to work with this UI. FFmpeg used by player engine should be compilled for LGPL, in shared dlls, to use player engine in commercial player without opening player sources to public.