ext/ffmpeg/gstffmpegcodecmap.c: Clarify some CODEC_ID <=> mime type conversions for image formats.
Original commit message from CVS: * ext/ffmpeg/gstffmpegcodecmap.c: (gst_ffmpeg_codecid_to_caps): Clarify some CODEC_ID <=> mime type conversions for image formats. * ext/ffmpeg/gstffmpegdemux.c: (gst_ffmpegdemux_register): Cleanup on demuxer registration. Bumped flv demuxer to RANK_MARGINAL since it proved solid enough. Will have to go over more demuxers, for which we don't have any gst-plugins-* alternative, to figure out which ones can move to RANK_MARGINAL too.