gst/mpegstream/gstmpegdemux.*: Complete overhaul. All DVD specific functionality...

gst/mpegstream/gstmpegdemux.*: Complete overhaul. All DVD specific functionality split to the new dvddemux element.

Original commit message from CVS:
* gst/mpegstream/gstmpegdemux.c:
* gst/mpegstream/gstmpegdemux.h: Complete overhaul. All DVD
specific functionality split to the new dvddemux element.
* gst/mpegstream/gstdvddemux.c:
* gst/mpegstream/gstdvddemux.h: New demultiplexer for DVD (VOB)
streams, derived from mpegdemux.
* gst/mpegstream/gstmpegparse.c: Discontinuity handling cleaned
up. SCR based timestamp rewriting can be turned off (will probably
completely disappear soon).
* ext/dvdnav/dvdnavsrc.c: Changes resulting from a few months
hacking. General cleanup. All printf statements replaced by
debugging messages. Almost complete libdvdnav support.
(dvdnavsrc_class_init): Got rid of unnecessary signals (replaced
by events. New properties for audio and subpicture languages.
(dvdnavsrc_update_highlight): Now uses events.
(dvdnavsrc_user_op): Cleaned up.
(dvdnavsrc_get): Renamed to dvdnavsrc_loop (element is now loop
based). Lots of cleanup, and propper support for most libdvdnav
events.
(dvdnavsrc_make_dvd_event): New function.
(dvdnavsrc_make_dvd_nav_packet_event): New function.
(dvdnavsrc_make_clut_change_event): New function.