Add hooks that contain protocol specific interfaces that can be used
to extend the protocol. This makes it possible to add new interfaces
to the protocol and implement the protocol specific data transport.
Move these protocol specific extension to the extensions directory.
Add GAsyncReadyCallback to the introspection API. This makes it possible
to report errors in the future. Don't pass NULL in the callback anymore
now that we have the Ready callback. We also don't need to have a return
value from the callback because now we can cancel any iteration by using
the GCancelable.
Make pinos_context_info_finish() to get the final result/error of
introspection.
Update tools for new API
