If we use a chain backend that only understands IP addresses (like
Neutrino for example), we need to turn any Onion v2 host addresses into
a fake IPv6 representation, otherwise it would be resolved incorrectly.
To do this, we use the same fake IPv6 address format that bitcoind and
btcd use internally to represent Onion v2 hidden service addresses.
In this commit, we fix an issue where connections made through Tor's
SOCKS proxy would result in the remote address being the address of the
proxy itself
We fix this by using an internal proxyConn struct that sets the correct
address at the time of the connection.
In this commit, we clean up the tor package to better follow the
Effective Go guidelines. Most of the changes revolve around naming,
where we'd have things like `torsvc.TorDial`. This was simplified to
`tor.Dial` along with many others.
