add remaining two unhinted baseline images
Update baseline images for hinting turned off.
buildbot: set exit code when running tests
store old rc params before tests and then update after
add test_image to default suite
Add an rcParam for hinting, and set it to False when running tests.
Reverting last change -- seems to have broken things
Update math_symbol_table directive to new Sphinx extension API
applied sf patch 2853659
add basic image interp unit test
