Using Bitcoin Core v0.15.1

I have just set `onlynet=onion` in my `bitcoin.conf` file and have the following in my logs after node restart:

    2018-02-03 12:40:52 receive version message: /Satoshi:0.15.1/: version 70015, blocks=507429, us={IPv4}:{port), peer=0
    2018-02-03 12:41:15 receive version message: /Satoshi:0.14.2/: version 70015, blocks=507429, us={IPv4}:{port), peer=2
    2018-02-03 12:41:22 receive version message: /Satoshi:0.14.2/: version 70015, blocks=507429, us={IPv4}:{port), peer=3
    2018-02-03 12:41:28 receive version message: /Satoshi:0.15.0/: version 70015, blocks=507429, us={IPv4}:{port), peer=4
    2018-02-03 12:41:57 receive version message: /Satoshi:0.15.99/: version 70015, blocks=526679, us={IPv4}:{port), peer=5
    ...
    2018-02-03 12:44:11 receive version message: /Satoshi:0.15.1/: version 70015, blocks=507429, us=[::]:0, peer=6

The peer 6 was an onion.

My `bitcoin.conf` file is as follows:

    uacomment={redacted}
    prune=10239
    banscore=10
    bantime=31536000
    maxmempool=900
    mempoolexpiry=2160
    proxy=127.0.0.1:9050
    listen=1
    bind=127.0.0.1
    onlynet=onion

All the `Used for reaching peers via` tick boxes are still ticked but disabled when I look in Options>Newtork.

Bitcoin Core should not initiate IPv4 (or IPv6) connections when `onlynet=onion`.  These connections should not be seed nodes due to low addresses:

    2018-02-03 12:40:30 Loaded 66198 addresses from peers.dat  254ms

I get some IPv4 version messages each time I restart the node.

Note: added both `dns=0` and `dnsseed=0` at the same time and this *seems* to resolve the issue with limited testing. These entries should not be necessary to limit IPv4 outgoing connect.

If people need to setup Tor for testing, the setup I have used is here on [Bitcoin.SE](https://bitcoin.stackexchange.com/a/70070/75001)
requested = Sock::SEND;
        } else if (select_recv) {
            requested = Sock::RECV;
        }
        events_per_sock.emplace(pnode->m_sock, Sock::Events{requested});
    }
    return events_per_sock;
}
void CConnman::SocketHandler()
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);
    Sock::EventsPerSock events_per_sock;
    {
        const NodesSnapshot snap{*this, false};
        const auto timeout = std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS);
        
        
        
        
        events_per_sock = GenerateWaitSockets(snap.Nodes());
        if (events_per_sock.empty() || !events_per_sock.begin()->first->WaitMany(timeout, events_per_sock)) {
            interruptNet.sleep_for(timeout);
        }
        
        SocketHandlerConnected(snap.Nodes(), events_per_sock);
    }
    
    SocketHandlerListening(events_per_sock);
}
void CConnman::SocketHandlerConnected(const std::vector<CNode*>& nodes,