Use diffsims for electron scattering and diffraction (#220)

* Introduce diffsims dependency, use diffsims' ReciprocalLatticePoint

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

* Add "Added" changelog entry explaining diffsims dependency

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

doc/changelog.rst

@@ -34,6 +34,9 @@ Added
   detector, which can be added to an EBSD signal as markers.
   (`#204 <https://github.com/pyxem/kikuchipy/pull/204>`_,
   `#219 <https://github.com/pyxem/kikuchipy/pull/219>`_)
+- Dependency on the diffsims package (https://github.com/pyxem/diffsims/) for
+  handling of electron scattering and diffraction.
+  (`#220 <https://github.com/pyxem/kikuchipy/pull/220>`_)
 
 Changed
 -------

kikuchipy/conftest.py

@@ -21,13 +21,13 @@
 import tempfile
 
 from diffpy.structure import Atom, Lattice, Structure
+from diffsims.crystallography import ReciprocalLatticePoint
 import numpy as np
 from orix.crystal_map import Phase
 from orix.quaternion.rotation import Rotation
 from orix.vector import Vector3d, neo_euler
 import pytest
 
-from kikuchipy.crystallography import ReciprocalLatticePoint
 from kikuchipy.detectors import EBSDDetector
 from kikuchipy.generators import EBSDSimulationGenerator
 from kikuchipy.signals import EBSD

kikuchipy/crystallography/__init__.py

@@ -21,12 +21,7 @@
 from diffpy.structure import Lattice
 import numpy as np
 
-from kikuchipy.crystallography.reciprocal_lattice_point import (
-    ReciprocalLatticePoint,
-)
-
 __all__ = [
-    "ReciprocalLatticePoint",
     "get_direct_structure_matrix",
     "get_reciprocal_structure_matrix",
     "get_reciprocal_metric_tensor",