Come up with a better way to deal with types.  Currently you either create
a new type or query the list.  There is little enough information at the
basic level that it can be a factory on some struct.  A more full-featured
type definition would contain a typefinder, etc.

Come up with a typefinder element, hooked into the plugin database.  Uses
DISCOVERY state to determine the type of data spewing out of a pad.

Add typefinders to the existing formats (au, wav, mp3, raw?).

Add time control capabilities to existing formats (above list).

Maybe make parser and builder classes just like src, sink, filter?

Write builders for au, wav.

Set up refcounting for buffers.

Determine flags necessary for buffers to be fully useful:
  GST_BUFFER_NO_FREE_ON_DESTROY - do I *not* free the data on destroy?
