Scikit-ued

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* Added the function :func:`bragg_peaks` to determine the location of single-crystal diffraction peaks in an image.
* Fixed deprecation warnings regarding NumPy's dtypes.

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* Improved :func:`autocenter` for diffraction patterns with large Ewald sphere walkoff.
* :func:`diffread` now supports NumPy's ``*.npy`` format.
* Speedup of all routines that use the Fast Fourier transform (:func:`autocenter`, :func:`align`, :func:`ialign`, :func:`itrack_peak`, and :func:`kinematicsim`) by 50%.

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* Added the :func:`autocenter` routine, to automatically find the center of diffraction patterns. This works for both single-crystal and polycrystalline patterns.
* `Support for Python 3.6 and NumPy<1.17 has been dropped <https://numpy.org/neps/nep-0029-deprecation_policy.html>`_

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This release brings major infrastructure improvements, which in turn have allowed to squash some bugs.

* Migration of continuous integration testing to GitHub Actions.
* Migration of test infrastructure to pytest.
* Tests are now included in source distributions.
* Code snippets in documentation are now tested for correctness.

User-facing changes:

* Fixed an issue where the detected shift in `skued.align` and `skued.ialign` might be partial (i.e. only shift in one direction).
* Fixed an issue with packaging data on Linux.
* The `fast` argument to `skued.align` and `skued.ialign` has been removed. It was previously-marked as deprecated.
* Added pre-emptive support for Python 3.10+ by removing deprecations.
* Increased the precision of the pseudo-voigt approximation in `skued.pseudo_voigt`.
* Fixed many issues regarding documentation being out-of-date.

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* `scikit-ued` is being re-licensed from the MIT license to the GPLv3 license.
* The `fast` argument to `skued.align` and `skued.ialign` has been deprecated. Its value has no effect anymore.
* Official support for Python 3.9.
* Removed explicit requirement for the `tifffile` package.

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* Added `skued.kinematicsim`, a simple function to compute electron diffraction patterns from
crystals structures in the kinematic approximation (i.e. thin samples).
* Added the `skued.RingArcSelection` area.
* Various documentation improvements and fixes.