Add some more links to walkthrough.rst

* Fix badly quoted block
* Add link to krondo's tutorial for newbies
* Add some links to internal classes and tor control spec.
moar ignore
pep8, flakes
pep8, flakes, readability improvements

* remove unused imports
* shorten lines
* minor readability improvements on some conditionals
Make test play nicely on OS X

Something odd with tempdirs that I don't wish to understand.
Merge remote-tracking branch 'kalikaneko/fix-refactor'
Note about cleanups from Kali Kaneko
add note about Gentoo
add note about exitaddr