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
update date2index function from netcdf4-python
update date2index docstring
update to latest version from netcdf4-python
applied sf patch 2853659
add basic image interp unit test
