Merge last round of Changelog updates for HTML 5 features.

Originally committed as revision 23278 to svn://svn.ffmpeg.org/ffmpeg/branches/0.6

Changelog

@@ -71,6 +71,13 @@ version 0.6:
 - spectral extension support in the E-AC-3 decoder
 - unsharp video filter
 - RTP hinting in the mov/3gp/mp4 muxer
+- Dirac in Ogg demuxing
+- seek to keyframes in Ogg
+- 4:2:2 and 4:4:4 Theora decoding
+- 35% faster VP3/Theora decoding
+- faster AAC decoding
+- faster H.264 decoding
+- low overhead Ogg muxing