Added methods to control theta position of r-ticklabels on polar plots
pep8 for backend_pdf.py
remove backend_pdf from pep8 test exclude list
minor code standard changes
minor code formatting
more informative exceptions for empty/not-existing images in
compare_images()
partial coloring of text: unicorn poop example
finish adding rainbow_text example, closes #697
adjust text size to fit in html docs
fixed naming and spacing issue, just for @pelson
ax is now an optional argument to rainbow_text

I hope @pelson and @tacaswell realize that this is just an example
gallery file when they were doing their code review
Correcting bad string comparsion in lin-log plot aspect verification
Merge pull request #2561 from ivanov/unicorn-fact

multi-colored text example
Merge pull request #2603 from fariza/aspect_auto_warning_bug

Correcting bad string comparsion in lin-log plot aspect verification
Fix download button
Merge pull request #2567 from megies/compare_image_exceptions

more informative exceptions for empty/not-existing images in compare_images()
Merge pull request #2549 from joferkington/add-rlabel-position

Add methods to control theta position of r-ticklabels on polar plots
Merge pull request #2459 from megies/pep8_backend_pdf

pep8 for backend_pdf.py
fixes issue #2482 and adds note about incompatibility between bbox options and animation backends
fixed a typo