Ported multipart mux/demux to 0.9.

Ported multipart mux/demux to 0.9.

Original commit message from CVS:
2005-11-30  Julien MOUTTE  <julien@moutte.net>

* configure.ac:
* PORTED_O9:
* gst/multipart/Makefile.am:
* gst/multipart/multipartdemux.c:
(gst_multipart_demux_base_init),
(gst_multipart_demux_class_init), (gst_multipart_demux_init),
(gst_multipart_find_pad_by_mime), (gst_multipart_demux_chain),
(gst_multipart_demux_change_state),
(gst_multipart_demux_plugin_init):
* gst/multipart/multipartmux.c: (gst_multipart_mux_class_init),
(gst_multipart_mux_init), (gst_multipart_mux_finalize),
(gst_multipart_mux_sinkconnect),
(gst_multipart_mux_request_new_pad),
(gst_multipart_mux_handle_src_event),
(gst_multipart_mux_queue_pads), (gst_multipart_mux_collected),
(gst_multipart_mux_change_state): Ported multipart mux/demux to
0.9.