Define microns as 1e-6 m

[clbarnes]

This resolves #1433, the non-equality with micrometers.
Also includes a test which previously failed and now passes.

• Closes # (insert issue number)
• Executed pre-commit run --all-files with no errors
• The change is fully covered by automated unit tests
• Documented in docs/ as appropriate
• Added an entry to the CHANGES file

[clbarnes]

This passes locally. However, I did find that I had to pip install the package again every time I changed the definitions file, even when the package was installed in editable mode. Without doing that, the test would pass in VScode, but fail when I called pytest (even in the terminal within VScode). This may be due to how package data files are handled, and this failure may relate to that by way of the pip cache.

[jules-ch]

We're install pint before testing with pip install ., I'll look into it.

[dalito]

I just tried this in a standard console (cmder/cmd on Win10). There it is not necessary to reinstall pint after changing the default registry file (default_en.txt). May it be related to VScode? A colleague had a somewhat similar problem with terminals in VScode this week.
Sorry, I initially misunderstood what you wrote.

[clbarnes]

I believe this can be closed now that #1476 has been merged.

[hgrecco]

Yes, but I am anyway keeping part of the test.