- changing an object's name after construction is not allowed. Checks are performed
  when adding objects to parents that no duplicate names are used, changing the name
  to a duplicate name after adding it is therefore allowed and voids internal
  consistency.

- implement return values from events in addition to the gboolean. This should be
  done by making the event contain a GstStructure with input/output values, similar
  to GstQuery. A typical use case is performing a non-accurate seek to a keyframe,
  after the seek you want to get the new stream time that will actually be used to
  update the slider bar.

- unlinking pads in the PAUSED state needs to make sure the stream thread is not
  executing code. Can this be done with a flush to unlock all downstream chain
  functions? Do we do this automatically or let the app handle this?

- implement clock selection as explained in part-gstpipeline.txt. 

- when a pipeline with a live source goes to PAUSED again, a sample is prerolled
  in the sinks. This sample should be discarded, possibly with a flush event
  started from the source.

- convert framerate to GstFraction in GstCaps.

- implement latency calculation for live sources.

- implement master/slave clocks.

- implement QOS.

- implement BUFFERSIZE.

- make bin_bus_handler a vmethod so subclasses can use their own implementation
  or chain to the parent.

- make it possible to seek on other formats than bytes in basesrc.

- GstFormat quarks, get_name. 

- GstQuery quark, get_name.

- GstEvent, GstMessage register like GstFormat or GstQuery.

- unblocking while seeking. gst_element_flush_pads (GstElement, gboolean);

- make GstCapsFlags instead of the #define for GST_CAPS_FLAGS_ANY.

- query POSITION/DURATION return accuracy. Just a flag or accuracy percentage.