EMsoft EBSD master pattern plugin can read a single energy, change energy parameter name

[hakonanes]

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

Description of the change

• An EMsoft master pattern file with a single beam energy pattern (e.g. only 20 keV) can now be read
• The energy_range parameter to the EMsoft master pattern reader is therefore changed to energy (in code and tests)
• Necessary updates to the tests and documentation are added.

This functionality is needed before PR #237 can progress, as a modified (uint8, not float32) single beam energy master pattern file is planned to be included in the kikuchipy.data module.

Progress of the PR

• Docstrings for all functions
• Unit tests with pytest for all lines
• Clean style in as per black

Minimal example of the bug fix or new feature

All these values to energy is now allowed:

>>> import kikuchipy as kp
>>> mp = kp.load("my/data.h5", energy=20)
>>> mp2 = kp.load("my/data.h5", energy=(10, 20))
>>> mp3 = kp.load("my/data.h5", energy=None)

For reviewers

• Check that the PR title is short, concise, and will make sense 1 year
  later.
• Check that new functions are imported in corresponding __init__.py.
• Check that new features, API changes, and deprecations are mentioned in
  the unreleased section in doc/changelog.rst.