Add gnomonic circles as patches to axes in EBSDDetector.plot()

[hakonanes]

Signed-off-by: Håkon Wiik Ånes hwaanes@gmail.com

Description of the change

• Add gnomonic circles as patches to axes in EBSDDetector.plot().
• This was done to fix Relax some axes_manager and metadata test comparisons in anticipation of HyperSpy v1.7 #332 so kikuchipy is (more) compatible with upcoming Matplotlib 3.5.0b1.

Progress of the PR

• Docstrings for all functions
• Unit tests with pytest for all lines
• Clean code style by running black via pre-commit

Minimal example of the bug fix or new feature

>>> import kikuchipy as kp
>>> detector = kp.detectors.EBSDDetector(shape=(80, 60))
>>> _, ax = detector.plot(coordinates="gnomonic", draw_gnomonic_circles=True, return_fig_ax=True)
>>> ax.artists  # Previous location of circles
<Axes.ArtistList of 0 artists>
>>> ax.patches  # Current location of circles
<Axes.ArtistList of 8 patches>
>>> ax.patches[:]
[<matplotlib.patches.Circle at 0x7fcdf85f9eb0>,
 <matplotlib.patches.Circle at 0x7fcdf85f9f10>,
 <matplotlib.patches.Circle at 0x7fcdf85f9a90>,
 <matplotlib.patches.Circle at 0x7fcdf85f90d0>,
 <matplotlib.patches.Circle at 0x7fcdf85f9430>,
 <matplotlib.patches.Circle at 0x7fcdf8571bb0>,
 <matplotlib.patches.Circle at 0x7fcdf8567520>,
 <matplotlib.patches.Circle at 0x7fcdf85679d0>]

For reviewers

• The PR title is short, concise, and will make sense 1 year later.
• New functions are imported in corresponding __init__.py.
• New features, API changes, and deprecations are mentioned in the unreleased
  section in doc/changelog.rst.
• New contributors are added to .all-contributorsrc and the table is regenerated.