In agent_receive_reply we first call the callback for the pending
request (agent_finalize_pending) then try to send the next request
in the queue. Check that the next request has not been sent already
which could happen if it has been just queued by the callback.
If the request being cancelled by agent_request_cancel has already been
sent over dbus we need to reset pending_id, the timeout, call l_dbus_cancel
to avoid the agent_receive_reply callback (and crash) and perhaps start
the next request. Alternatively we could only reset the callback and not
free the request, then wait until the agent method to return before starting
the next request.
If an application initiates the Connect() operation and
that application has an agent registered, then that
application's agent will be called. Otherwise, the default
agent is called.
Use the org.freedesktop.DBus.Properties interfaces on objects with
properties and drop the old style GetProperty/SetProperty methods on
individual interfaces. Agent and KnownNetworks have no properties at
this time so don't add org.freedesktop.DBus.Properties interfaces.
