Path support

[erooke]

For all import / export methods make the path a Union[Pathlike, str, bytes] argument to follow python conventions as outlined in pep 519.

closes: #685
closes: #774

I got carried away big time and this PR is probably unreasonably large. To test the new functionality I changed all the tests to feed in pathlib.Paths. In addition any tests which wrote to disk were rewritten to use the pytest tmp_path fixture. Which then caused me to rewrite the tests in the pytest style...

I can revert the test changes and be less invasive with my changes if desired.

Edit: I decided to roll those back. I think they're good changes in the long run but they get in the way of reviewing the pr at hand.

Open questions:

• should the deprecated export methods in topology.py also be moved over to this scheme? Technically that is what Feature Request: Add support for exports to pathlib.Path: .export_stl(path_object) #685 is requesting
• should the tests attempt to verify that all three types: string, paths, and bytes work? I added said tests
• did I miss any exporting/importing methods

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.10%. Comparing base (af60811) to head (80fc373).
Report is 10 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #787      +/-   ##
==========================================
+ Coverage   96.09%   96.10%   +0.01%     
==========================================
  Files          25       25              
  Lines        8472     8481       +9     
==========================================
+ Hits         8141     8151      +10     
+ Misses        331      330       -1     

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[gumyr]

For my education, what does the input type bytes actually do here? Why would a user pass bytes - is it for unicode file names?

[gumyr]

There is no need to refactor the deprecated export methods.

[erooke]

For my education, what does the input type bytes actually do here? Why would a user pass bytes - is it for unicode file names?

I am not 100% sure. It seems to be a leftover from the fact that the c standard library used raw byte strings to represent paths. There is some discussion in pep 519 here. I included it in the signature because all of the underlying Pathlike functions support it and they claim:

In the end, it was decided that using bytes to represent paths is simply not going to go away and thus they should be supported to some degree. The hope is that people will gravitate towards path objects like pathlib and that will move people away from operating directly with bytes.

[gumyr]

Thank you! Another nice improvement.

[DeflateAwning]

Thank you! I've been looking forward to this very small quality-of-life improvement :)