[tor-dev] use sphinx on stem

[Damian Johnson]

Hi Beck. It's a pity that you disappeared from irc, I tried to tell
you there that I was actively looking into Sphinx too and had some
discussions in #tor-dev about if we should switch to reStructuredText.

I'm currently converting all of our pydocs and will probably be done tomorrow...
https://gitweb.torproject.org/user/atagar/stem.git/shortlog/refs/heads/sphinx

I'm probably doing a poor job of coordinating things. Thoughts on what
we could do better to avoid stepping on each other's toes?