Apply and conform to better linting

[jwodder]

Includes the commit from #196.

This revealed a typing error which appears to be a genuine bug.

[a-detiste]

thanks

[yarikoptic]

duecredit/io.py:396: error: Argument 1 to "get_bibtex_rendering" has incompatible type "DueCreditEntry"; expected "Union[Doi, BibTeX]"  [arg-type]
Found 1 error in 1 file (checked 50 source files)

Happy Thanksgiving!!!

[jwodder]

@yarikoptic Yes, that's the bug I found. As far as I can tell, mypy is right to complain: the code is trying to pass a DueCreditEntry to a function that doesn't accept DueCreditEntrys, and I don't know what the intention behind the code is.

(The reason mypy is complaining now is because, after the import fix that @a-detiste commented on above, mypy now knows what a Citation is and what its entry attributes are.)

[codecov-commenter]

Codecov Report

Attention: 31 lines in your changes are missing coverage. Please review.

Comparison is base (13a0cd5) 81.50% compared to head (915fdd3) 81.29%.
Report is 6 commits behind head on master.

❗ Current head 915fdd3 differs from pull request most recent head ea49b39. Consider uploading reports for the commit ea49b39 to get more accurate results

Files	Patch %	Lines
duecredit/utils.py	6.66%	14 Missing ⚠️
duecredit/io.py	61.53%	5 Missing ⚠️
duecredit/__main__.py	42.85%	2 Missing and 2 partials ⚠️
duecredit/cmdline/helpers.py	50.00%	1 Missing ⚠️
duecredit/cmdline/main.py	75.00%	0 Missing and 1 partial ⚠️
duecredit/collector.py	50.00%	1 Missing ⚠️
duecredit/injections/injector.py	83.33%	1 Missing ⚠️
duecredit/log.py	75.00%	1 Missing ⚠️
duecredit/tests/test_api.py	75.00%	1 Missing ⚠️
duecredit/tests/test_dueswitch.py	87.50%	1 Missing ⚠️
... and 1 more

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #197      +/-   ##
==========================================
- Coverage   81.50%   81.29%   -0.21%     
==========================================
  Files          47       47              
  Lines        2546     2545       -1     
  Branches      361      359       -2     
==========================================
- Hits         2075     2069       -6     
- Misses        380      385       +5     
  Partials       91       91              

Flag	Coverage Δ
unittests	81.17% <78.16%> (-0.21%)	⬇️

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[yarikoptic]

for now I think the best would be to just make it accept DueCreditEntry as type... I also RFed the get_text_rendering to accept DueCreditEntry as well instead of Citation. Will rebase to resolve conflicts now