Fall 2021, expand testing to python 3.9

Merge pull request #78 from phobson/follow-linter

take the linter's advice

Merge pull request #50 from phobson/phobson-refs

few more refs to the phobson fork

Merge pull request #49 from phobson/cleanup-tutorial-figs

Cleanup tutorial figs

Merge pull request #47 from matplotlib/mpl-readme

update readme for new ownership

Merge pull request #37 from phobson/bump-to-v0.2.2

bump to v0.2.2

Merge pull request #35 from phobson/py27-img-tolerance

loosen probscale test tolerance

Merge pull request #29 from phobson/docs-2

minor doc cleanups

Merge pull request #16 from phobson/docs-release-0.1.2

Docs release 0.1.2

Merge pull request #13 from phobson/diy-plotting-positions

DIY plotting positions