Add reader for EMsoft's simulated EBSD patterns

[hakonanes]

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

Description

• Reader for simulated EBSD patterns from EMsoft's program EMEBSD.
• Add helpful writing of original metadata to metadata DictionaryTreeBrowser (HyperSpy) from mapping

Checklist

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

Minimal example of the bug fix or new feature

>>> import kikuchipy as kp
>>> ss = kp.load("my_emsoft_ebsd_file.h5")
>>> ss
<EBSD, title: ni1_sda_sim, dimensions: (29800|60, 60)>

# Provide a navigation shape (note that HyperSpy flips row, col in string representation)

>>> ss2 = kp.load("my_emsoft_ebsd_file.h5", scan_size=(149, 200))
>>> ss2
<EBSD, title: ni1_sda_sim, dimensions: (200, 149|60, 60)>

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.

[hakonanes]

Referring back to our discussion IRL yesterday, @friedkitteh and @onatlandsmyr, I think it is best to read simulated patterns from EMsoft into the kikuchipy.signals.EBSD class, instead of creating a new kikuchipy.signals.SimulatedEBSD. Just because it is simpler to maintain one class instead of two, and I don't think there are many methods or attributes that are specific to either experimental or simulated patterns.

[hakonanes]

While the pattern centre (xpc, ypc, L or zpc) is read from the EMsoft simulated EBSD file, the orientations used to simulate the patterns (Euler angle triplets) are not read yet. We first need to add a EBSD.xmap attribute containing a orix.crystal_map.CrystalMap object. All orientation and crystal structure stuff will be handled through that attribute. Will try to set up a work in progress (WIP) PR right away to get this.