Add minimal typing (and assorted cleanups) #183

Job	Run time
Test (windows-latest, 3.8)	1m 39s
Test (macos-latest, 3.8)	54s
Test (windows-latest, 3.9)	1m 39s
Test (ubuntu-20.04, 3.8)	52s
Test (macos-latest, 3.9)	40s
Test (ubuntu-20.04, 3.9)	38s
Test (windows-latest, 3.10)	1m 37s
Test (macos-latest, 3.10)	30s
Test (ubuntu-20.04, 3.10)	37s
Test (windows-latest, 3.11)	1m 40s
Test (macos-latest, 3.11)	29s
Test (windows-latest, 3.12)	1m 41s
Test (macos-latest, 3.12)	29s
Test (ubuntu-20.04, 3.11)	30s
Test (windows-latest, pypy-3.8)	2m 5s
Test (macos-latest, pypy-3.8)	39s
Test (ubuntu-20.04, 3.12)	1m 11s
Test (windows-latest, pypy-3.9)	1m 43s
Test (macos-latest, pypy-3.9)	37s
Test (ubuntu-20.04, pypy-3.8)	40s
Test (windows-latest, pypy-3.10)	1m 32s
Test (macos-latest, pypy-3.10)	46s
Test (ubuntu-20.04, pypy-3.9)	42s
Test (ubuntu-20.04, pypy-3.10)	41s
Build wheels on ubuntu-20.04 for auto	2m 56s
Build wheels on windows-latest for auto	6m 13s
Build source distribution	7s
Build wheels on macos-latest for auto	1m 45s
Generate code coverage report	0s
Build wheels on ubuntu-20.04 for aarch64	7m 23s
Build wheels on macos-latest for arm64	1m 51s
	44m 46s

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