theora decoding support (only keyframes for now, because by theora the frame isn't flipped so the motion vectors are getting screwed up)

Originally committed as revision 2359 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/allcodecs.c

@@ -117,6 +117,7 @@ void avcodec_register_all(void)
     register_avcodec(&cyuv_decoder);
     register_avcodec(&h264_decoder);
     register_avcodec(&vp3_decoder);
+    register_avcodec(&theora_decoder);
     register_avcodec(&asv1_decoder);
     register_avcodec(&asv2_decoder);
     register_avcodec(&vcr1_decoder);