Original commit message from CVS:
* gst-libs/gst/interfaces/Makefile.am:
* gst-libs/gst/interfaces/interfaces-marshal.list:
* gst-libs/gst/interfaces/rtspextension.c:
(gst_rtsp_extension_iface_init),
(gst_rtsp_extension_stream_select), (gst_rtsp_extension_send):
* gst-libs/gst/interfaces/rtspextension.h:
Fix marshaller for the send signal.
Add URL to stream selection interface method.