gst/gstmessage.*: Added a bunch of messages for advanced seeking.

gst/gstmessage.*: Added a bunch of messages for advanced seeking.

Original commit message from CVS:
* gst/gstmessage.c: (gst_message_new_segment_start),
(gst_message_new_segment_done), (gst_message_parse_segment_start),
(gst_message_parse_segment_done):
* gst/gstmessage.h:
Added a bunch of messages for advanced seeking.

* gst/parse/grammar.y:
* libs/gst/control/dparammanager.c: (gst_dpman_set_parent),
(gst_dpman_state_changed):
Fix some new-pad -> pad-added signals