support for adding new components (syntax: ffmpeg -i input_file [output options] output_file [[component output options] {-newaudio|-newvideo|-newsubtitle}]... - added subtitle support - added '-alang' option


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@4351 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b