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

{
    size_t ptr=0;
    std::string type;
    while (ptr < s.size() && s[ptr] != ' ') {
        type.push_back(s[ptr]);
        ++ptr;
    }
    if (ptr < s.size())
        ++ptr; 
    return make_pair(type, s.substr(ptr));
}
/** Parse reply arguments in the form 'METHODS=COOKIE,SAFECOOKIE COOKIEFILE=".../control_auth_cookie"'.
 * Returns a map of keys to values, or an empty map if there was an error.
 * Grammar is implicitly defined in https://spec.torproject.org/control-spec by
 * the server reply formats for PROTOCOLINFO (S3.21), AUTHCHALLENGE (S3.24),
 * and ADD_ONION (S3.27). See also sections 2.1 and 2.3.
 */
std::map<std::string,std::string> ParseTorReplyMapping(const std::string &s)