gst/: Active pads before adding them to the running element. Don't assert on non...

gst/: Active pads before adding them to the running element. Don't assert on non-BYTE format newsegment events in asf...

Original commit message from CVS:
* gst/asfdemux/gstasfdemux.c: (gst_asf_demux_sink_event),
(gst_asf_demux_setup_pad), (gst_asf_demux_process_segment):
* gst/mpegstream/gstdvddemux.c: (gst_dvd_demux_get_audio_stream),
(gst_dvd_demux_get_subpicture_stream):
* gst/mpegstream/gstmpegdemux.c: (gst_mpeg_demux_get_video_stream),
(gst_mpeg_demux_get_audio_stream),
(gst_mpeg_demux_get_private_stream):
Active pads before adding them to the running element. Don't assert
on non-BYTE format newsegment events in asfdemux.