Original commit message from CVS:
* ext/ogg/gstoggdemux.c: (gst_ogg_demux_src_query),
(gst_ogg_demux_src_event), (gst_ogg_pad_push):
Start at zero.
* ext/theora/theoradec.c: (theora_dec_chain):
Skip headers. Bad idea for chained ogg, but fixes seeking.