add support for more audio/video formats/extensions:
 * video: mp4, mpg, mpeg, mov, avi, wmv, flv, webm
 * audio: .aiff, .aif, .wma, .aac, .flac, .mp3, .ogg, .m4a
 * use Nitrux icons (http://deviantn7k1.deviantart.com/art/Nitrux-293634207) for audio and video icons