Added docs for Player.areFullShadersSupported.

git-svn-id: https://www.libavg.de/svn/trunk/libavg@9258 44470bb9-56e9-0310-a0f8-c586564d3dc6
Removed bogus error messages for older ffmpeg.

git-svn-id: https://www.libavg.de/svn/trunk/libavg@9259 44470bb9-56e9-0310-a0f8-c586564d3dc6