proxy rpc
After much discussion; The proxies will communicate with idl defined messages
and NDR encoding sent by ntioctl within the session.
There will therefore be an implicit fnum associated with the ntioctl which
identifies the file on which the proxy function is to operate.
I'm not entirely happy with that out-of-band-data so that may change to be IN
the NDR encoded data as well; but the tid and session is also out-of-band and
used to interpret the fnum anyway, so maybe we won't worry about that right now.