Piva

Added

- Proper k-space conversion routine for both manipulator & photon energy scans.
Uses a "rescaling" approach to account for momentum conservation, instead of
previous simple swapping of axes values.

Changed

- Python version >3.8 is now required, rather than previous >3.7.

Fixed

- Issue 28: colorscales now work as expected again.
- Appearance issues of `QTabWidget` on Windows.
- Several small bugfixes.

Fixed

- Issue 27 & 33: Save button now working properly.
- Issue 29: Commented a part of the code in `cmaps.py` which was attempting
to load `data-slicer` colormaps. See issue 29. PIT now opening from piva.
- Issue 30: Inverting colorscale in 2D viewer.
- Issue 31: c-axis field accepts values beyond 10 Angstrom.
- Issue 32: metadata-window now has a scrollbar.

Added

- "Open in PIT" button

Changed

- `db` function (also `python -m piva.main`) now displays current version
number on startup.

Fixed

- wheel and source packages differed on pypi.

First official release.