Greatly improve reading of EBSD patterns from Oxford Instruments' binary .ebsp file format

[hakonanes]

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

Description of the change

This PR greatly improves reading of EBSD patterns from Oxford Instruments' binary .ebsp file format.

With this addition, kikuchipy should be able to read .ebsp files with these contents:

• Pattern bit depth of either 8 (0-255) or 16 (0-65535) unsigned integers (determined from pattern header information).
• Only non-indexed patterns are stored in the file (determined from non-zero "pattern starts" in the file header). In this case the navigation shape will always be 1D.

As long as beam positions are stored in the pattern footer information (not the case for all .ebsp file versions), the navigation/map shape is automatically determined. Otherwise, the navigation shape can be provided. The signal/detector shape is always available in the file (pattern header).

This reader will be released as part of v0.4. There will surely be some bugs that will need to be sorted out, which can be done in patch releases.

Progress of the PR

• Finish reader
• Improve test setup so that a dummy .ebsp file is created upon testing, then deleted again
• Changelog entry
• 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 hyperspy.api as hs
>>> import kikuchipy as kp
>>> s = kp.load("patterns.ebsp")  # Can have uint8/uint16 patterns, or only non-indexed patterns
>>> iq = s.get_image_quality()
Calculating the image quality:
[########################################] | 100% Completed |  2.8s
>>> s.plot(navigator=hs.signals.BaseSignal(iq))

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.

[hakonanes]

This reader now works on files I received from @mikesmic, @CiosG (not the file with compressed patterns) and @IMBalENce, thanks a lot to you all!

I'll merge after checks pass, and then prepare a v0.4 release for tomorrow Thursday.