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
get rid of unused variables
Honour ControlPort=0 in launch_tor() (issue 80)

This allows you to pass in a ControlPort of 0 to the launch_tor
method, which causes no control connection to be established. In this
case, you must kill the tor off yourself and need to figure out when
it's bootstrapped "somehow".
Add note about issue 80 fix