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

int nProtLevel = PROTECTION_LEVEL_UNRESTRICTED;
        setsockopt(hListenSocket, IPPROTO_IPV6, IPV6_PROTECTION_LEVEL, (const char*)&nProtLevel, sizeof(int));
#endif
    }
    if (::bind(hListenSocket, (struct sockaddr*)&sockaddr, len) == SOCKET_ERROR)
    {
        int nErr = WSAGetLastError();
        if (nErr == WSAEADDRINUSE)
            strError = strprintf(_("Unable to bind to %s on this computer. %s is probably already running."), addrBind.ToString(), PACKAGE_NAME);
        else
            strError = strprintf(_("Unable to bind to %s on this computer (bind returned error %s)"), addrBind.ToString(), NetworkErrorString(nErr));
        LogPrintf("%s\n", strError.original);
        CloseSocket(hListenSocket);
        return false;
    }
    LogPrintf("Bound to %s\n", addrBind.ToString());
    
    if (listen(hListenSocket, SOMAXCONN) == SOCKET_ERROR)
    {
        strError = strprintf(_("Error: Listening for incoming connections failed (listen returned error %s)"), NetworkErrorString(WSAGetLastError()));
        LogPrintf("%s\n", strError.original);
        CloseSocket(hListenSocket);
        return false;
    }
    vhListenSocket.push_back(ListenSocket(hListenSocket, permissions));
    if (addrBind.IsRoutable() && fDiscover && (permissions & PF_NOBAN) == 0)
        AddLocal(addrBind, LOCAL_BIND);
    return true;
}
void Discover()