Sum Lambert projections from asymmetric positions in EMsoft plugin

[hakonanes]

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

Description of the change

• Fix Lambert proj. read incorrectly from EMsoft MP files of crystal structures with more than one asymmetric atom positions #249.
• Disable divide-by-zero numpy warning in Lambert projection test.
• Add TODO comment expressing the need to move IO plugins towards a class based design.
• Update "Fixes" changelog list.

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

Reading Lambert projections from EMsoft's master pattern files with a crystal structure with multiple asymmetric atom positions now sums the Lambert projections per energy bin correctly in the IO plugin

>>> import kikuchipy as kp
>>> mp = kp.load("master_pattern.h5", projection="lambert")

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.