Handle custom EBSD class attributes in calls to Signal2D's inav, isig and more

Description of the change

Attempt to crop and update EBSD class attributes xmap (an orix CrystalMap), static_background and detector (an EBSDDetector) upon calls to the following inherited methods from HyperSpy's Signal2D methods:

inav (crop xmap and EBSDDetector.pc)
isig (crop EBSDDetector.shape and static_background)
crop() (crop attributes)
crop_image() (crop EBSDDetector.shape and static_background)
rebin() (if nav dimensions change, the xmap and EBSDDetector.pc values are lost; if only sig dimensions change, EBSDDetector.pc values are lost while the static_background is binned similarly to the signal)

Handling of attributes in inav and isig is done by overwriting the private BaseSignal._slicer() method. This is dangerous, however most handling is done via try/except, falling back to old behavior if this doesn't work. Tests, my own testing and building the docs' tutorials and examples runs as desired.

Other changes:

Added crystal map and refined PC values to the nickel_ebsd_small() dataset HDF5 file. Indexing and PC refinement was done first with PyEBSDIndex, then using refine_orientation_projection_center().
Improved handling of detector PC values in the kikuchipy h5ebsd file reader

Closes #227.

Progress of the PR

[x] Docstrings for all functions
[x] Unit tests with pytest for all lines
[x] Clean code style by running black via pre-commit
[x] Update detector PC values correctly after cropping the signal shape (in isig, crop, crop_image)
[x] Update detector binning when calling rebin()
[x] Examples demonstrating selection of data (isig, inav, crop, crop_image)

Minimal example of the bug fix or new feature

>>> import kikuchipy as kp
>>> s = kp.data.nickel_ebsd_small()
>>> s
<EBSD, title: patterns Scan 1, dimensions: (3, 3|60, 60)>
>>> s.xmap.shape
(3, 3)
>>> s.static_background.shape
(60, 60)
>>> s.detector
EBSDDetector (60, 60), px_size 1 um, binning 8, tilt 0, azimuthal 0, pc (0.425, 0.213, 0.501)

# Bin signal shape by a factor of 2 (can call remove_static_background() afterwards without modifications to
# background pattern)

>>> s2 = s.rebin(scale=(1, 1, 2, 2))
>>> s2
<EBSD, title: patterns Scan 1, dimensions: (3, 3|30, 30)>
>>> s2.xmap.shape
(3, 3)
>>> s2.static_background.shape
(30, 30)
>>> s2.detector
EBSDDetector (30, 30), px_size 1 um, binning 8, tilt 0, azimuthal 0, pc (0.425, 0.213, 0.501)

# Crop

>>> s.inav[:2, :1].xmap.shape
(1, 2)
>>> s.isig[10:50, 10:].static_background.shape
(50, 40)
>>> s.inav[:2, :3].detector.pc.shape
(3, 2, 3)

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 CHANGELOG.rst.
[ ] New contributors are added to release.py, .zenodo.json and .all-contributorsrc with the table regenerated.

pyxem / kikuchipy