To be able to label incoming tor connections as different from normal localhost connections in e.g. `getpeerinfo` and the peers list in the GUI it'd be useful to have them connect on an alternative local-only port. Or even better, a UNIX socket.

For manually set-up hidden services this would have to be configured manually and could add a `hsport` option or such. The external port would still appear as `XXXXXXXXX.onion:8333`, however internally it would redirect to a that port.

In the case of `torcontrol` this would be easy to set up automatically. It could add a new (localhost) binding port automatically and this code would have to be changed:
- https://github.com/bitcoin/bitcoin/blob/master/src/torcontrol.cpp#L441
- https://github.com/bitcoin/bitcoin/blob/master/src/torcontrol.cpp#L477

{
    while (!interruptNet)
    {
        DisconnectNodes();
        NotifyNumConnectionsChanged();
        SocketHandler();
    }
}
void CConnman::WakeMessageHandler()
{
    {
        LOCK(mutexMsgProc);
        fMsgProcWake = true;
    }
    condMsgProc.notify_one();
}
#ifdef USE_UPNP
static CThreadInterrupt g_upnp_interrupt;
static std::thread g_upnp_thread;
static void ThreadMapPort()