Removes completed TODO re: scientific Python
Adds Sphinx to requirements.txt
Correct spelling of 'aforementioned'.
Nitpicky rewordings and grammar fixes.
Add line breaks for conformance with the Style Guide.
GtK --> GTK
'many' --> 'much'
PEP and Python are capitalized.
'async' --> 'asynchronous'
Code block type is 'console', not 'bash'.
Added note about OSX-GCC-Installer and Xcode conflict.
Fix link to Dive Into Python 3
minor formatting changes.
Merge pull request #286 from artloder/minor-changes

Minor formatting changes.
Merge pull request #285 from puppe/patch-1

Fix link to Dive Into Python 3
Merge pull request #284 from kuyan/master

Grammar, capitalization fixes
Merge pull request #282 from lyndsysimon/master

Housekeeping
Fix link to tox documentation.
Merge pull request #290 from rvanlaar/patch-1

Fix link to tox documentation.
Fix enumerate code snippet to run without error message

Code previously added numbers to strings, which results in a TypeError