check/states/sinks.c: Added some more checks. Specifically the case where NO_PREROLL elements are in the pipeline.

Original commit message from CVS:
* check/states/sinks.c: (GST_START_TEST), (gst_object_suite):
Added some more checks. Specifically the case where NO_PREROLL
elements are in the pipeline.

* gst/base/gstbasesink.c: (gst_base_sink_commit_state),
(gst_base_sink_handle_object), (gst_base_sink_do_sync),
(gst_base_sink_get_position):
Post READY->PAUSED state change messages too.
Fix bug where VOID was posted as pending state...

* gst/gstbin.c: (gst_bin_recalc_state):
use _element_continue_state() to continue the state change.

* gst/gstelement.c: (gst_element_continue_state),
(gst_element_commit_state), (gst_element_set_state_func),
(gst_element_change_state), (gst_element_change_state_func):
Lots of state change cleanups, assign the STATE_RETURN in
a new continue_state() function that also propagates the
last return value from a state change to the app.
Update some debug statements with proper category.