#268
small formatting cleanup
Merge pull request #272 from kuyan/master

Various improvements to OS X installation guide
update URI of location of latest version of Python from 2.7.3 to 2.7.4
Merge pull request #274 from dominiqueplante/windows-install-updatelatestversionto2.7.4

Windows install update- update link to latest version to 2.7.4
reapply some improvements to code style section in different branch
Merge pull request #278 from dominiqueplante/writingSection

reapply some improvements to code style section in different branch
Update env.rst
Merge pull request #280 from ugurthemaster/master

update env.rst
Update scientific.rst

Description about Numba has been added.
Update scientific.rst
Merge pull request #281 from ugurthemaster/master

Update scientific.rst
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'.