Implement prop229 ("Further SOCKS5 extensions")
In proposal 229, Yawning describes a few improvements to the SOCKS5 protocol for better use by Tor-aware tools.
We should implement that.
(I'm putting this ticket in 0.2.??? since I don't think I'll be able to do it on an 0.2.6 timeframe, but if somebody else does the coding, it might be able to get done sooner.)