Merge branch 'dev'

DOC: Add table of migrating v0.4.16 to v0.5.0 to changes.rst.

Also update the README to link to the migration table.

Merge branch 'release/v0.5.0.dev2' into dev

DEV: Flatten "docs" into "dev" dependencies. Version -> 0.5.0.dev1.

PEP 621 prohibits referencing dependency lists from other dependency
lists, so just put all the requirements into [dev].

Merge branch 'release/v0.5.0.dev0' into independent-dev

Merge pull request #137 from AaronDJohnson/update_ci

Fix deployment: attempt 2

Merge pull request #126 from AaronDJohnson/fix_build_sdist

Fix build sdist

Merge pull request #121 from AaronDJohnson/fix_deployment

Make upload directory match build directory in deployment

Merge pull request #119 from AaronDJohnson/fix_ci

Increment version number

Merge pull request #118 from AaronDJohnson/fix_ci

make python 3.6, 3.7 run on old Mac version