Documentation updates.

Documentation updates.

Original commit message from CVS:
* docs/gst/gstreamer-sections.txt:
* gst/gstbin.c: (bin_bus_handler), (gst_bin_handle_message_func):
* gst/gstbin.h:
* gst/gstbus.c: (gst_bus_class_init):
* gst/gstbus.h:
* gst/gstclock.c:
* gst/gstelement.c: (gst_element_set_locked_state):
* gst/gstsegment.c:
Documentation updates.
* gst/gstpipeline.c: (gst_pipeline_get_type),
(gst_pipeline_class_init), (gst_pipeline_init),
(gst_pipeline_dispose), (gst_pipeline_set_property),
(gst_pipeline_get_property), (do_pipeline_seek),
(gst_pipeline_send_event), (gst_pipeline_change_state),
(gst_pipeline_provide_clock_func), (gst_pipeline_set_delay),
(gst_pipeline_get_delay):
* gst/gstpipeline.h:
Added methods for setting the delay.
API: gst_pipeline_set_delay
API: gst_pipeline_get_delay
Add pipeline debug category
Various cleanups.
Updated docs.
Don't reset stream time when seek failed.