arti, tor-config: Allow listening on generic addresses for SOCKS and DNS.

First attempt at allowing multiple non-localhost addresses for the SOCKS and DNS proxies to listen on.

This seems to make the ListenUnsupported error and the localhost_port_legacy method unnecessary but they are left there (possibly needed for backwards compatibility).

Proper handling of various errors probably needs to be done differently, right now AddrInUse only is treated as a serious error.