gst/: API change fix.

gst/: API change fix.

Original commit message from CVS:
* gst/base/gstbasesink.c: (gst_base_sink_commit_state),
(gst_base_sink_handle_object), (gst_base_sink_query), (do_playing):
* gst/base/gstbasesrc.c: (gst_base_src_query):
* gst/elements/gstfilesink.c: (gst_file_sink_query):
* gst/elements/gsttypefindelement.c:
(gst_type_find_handle_src_query), (find_element_get_length),
(gst_type_find_element_activate):
API change fix.

* gst/gstquery.c: (gst_query_new_position),
(gst_query_set_position), (gst_query_parse_position),
(gst_query_new_duration), (gst_query_set_duration),
(gst_query_parse_duration), (gst_query_set_segment),
(gst_query_parse_segment):
* gst/gstquery.h:
Bundling query position/duration is not a good idea since duration
does not change much and we don't want to recalculate it for every
position query, so they are separated again..
Base value in segment query is not needed.

* gst/gstqueue.c: (gst_queue_handle_src_query):
* gst/gstutils.c: (gst_element_query_position),
(gst_element_query_duration), (gst_pad_query_position),
(gst_pad_query_duration):
* gst/gstutils.h:
Updates for query API change.
Added some docs here and there.