Use ORPort control to change nyms over SOCKS switching.

Right now parcimonie.sh depends on circuit-switching for every different
username:password combo passed to SOCKS.[1]

I also use some keyserver-options from the Tor project's work on
TorBirdy[2] to avoid DNS leaks but these probably fit better elsewhere
in this script.

[1]: https://github.com/EtiennePerot/parcimonie.sh/commit/1598184c08e1cedf99d596d093b63fefe1212522#L0R9
[2]: https://trac.torproject.org/projects/tor/ticket/2846