Xrayutilities

* fix data type casting of cch1,2 in QConversion.init_area -> these can now be floating point values (141 by trdd)
* fix docstring for March-Dollase texture model in xu.simpack.Powder. The
parameter preferred_orientation_factor was described wrong. Platy crystals
need a factor < 1! see W. A. Dollase, J. Appl. Cryst. (1986). 19, 267-272
* fix Poisson ratio of GaInAs Darwin model (thanks to Danny Chrastina for
reporting)
* Additional convenience functions for elasticity tensor symmetries for
Monoclinic and Trigonal symmetry (138 by f-iniv)
* GetStrain and GetStress functions for xu.material.Material (138 by f-iniv)
* enable correct parsing of Seifert RSM map measurements
* matplotlib format bugfix in psd_chdeg
* improvements for kappa goniometers
* remove use of deprecated scipy namespace

* enable building Python 3.10 wheels
* fix missing files in source package on PyPI
* make builddocs pipeline more robust

* fix returned fitting error in area_detector_calib* (issue 126)
* remove dependency on soon deprecated distutils
* fix regression bug with matplotlib 3.5
* update copyright notices from git commit history
* fix code error found by linting (flake8)
* CIF atom type normalization of oxidation state (issue 122)
* improve documentation of PowerModel multiprocessing code (issue 121)
* fix numpy-1.20 deprecation warnings
* bugfix in kinematical diffraction model.
* add visualization of individual layer densities (issue 107)
* new coplanar_alphaf helper function

* harmonize dependency versions between README and setup.py
* remove PDF documentation and other generatable content from the GIT
repository
* new azure pipeline for documentation generation
* new azure pipeline for wheel generation (issue 111)

* allow string decoding to fail in tif headers
* ignore nan values in maplog
* add Azure pipeline for continuous testing and automatic builds
* performance optimizations in Crystal.environment
* Continous integration tests running on MacOS, Windows and Linux
* new flavor of material/Crystal definition from fractional atomic coordinates
* bugfix in derivative functions (xu.math.functions)
* effectiveDensity slicing for XRR simulations, thanks to MM
* new possibility to transform unit cells and find symmetries
* bugfix of numpy.set_printoptions use
* require Python 3.6 due to use of f-strings
* new PowderModel.plot method to quickly visualize a Powder pattern
* remove deprecated fit_xrr function
* SGLattice.get_allowed_hkl function
* make SGLattice.convert_to_P1 a normal method
* SGLattice improvements: add symmetry operations, equivalent_hkls,
reflection_conditions, and allowed_hkl functionality
* fix SGLattice.isequivalent function to work for non-centrosymmetric
materials
* implementation of the March-Dollase model for preferred orientation in
PowderDiffraction
* Mayavi based visualization of unit cells: Crystal.show_unitcell
-> new optional dependency on Mayavi
* fix new Pilatus TIFF files which seem to have \xff padding
* implement Gaussian beam shape for XRR modelling
* update documentation to recommend the use of pip for installation
* remove multGaussFit/Plot and set multPeakFit/Plot deprecated
-> use the much more powerful lmfit-package instead!
* rename dummy element to "Dummy" and set sensible default parameters

* use of tox to run unittests consistently in a virtual environment
* build element database during installation from sources
* new source layout which offers many advantages
(https://blog.ionelmc.ro/2014/05/25/python-packaging/#the-structure)
* remove Python2 code path, improve code readability
* fix use of the agg matplotlib backend with FitModel
* from this point on Github master will be broken on Python 2