Ncvue

* Work with files without an unlimited (time) dimension.
* Removed bug in detection of lon/lat.
* Identify lon/lat also by axis attributes x/y or X/Y.
* Do not default the unlimited dimension to 'all' if no lon/lat were found.

* Use Azure theme v2.0 on Linux and Sun Valley theme v1.0 on Windows from
rdbende (https://github.com/rdbende).
* Does not provide standalone package (no installer) on macOS with Apple
Silicon (M1) chip anymore (no paid Apple Developer ID).

* Separate variables and dimensions by space again but deal with space in
variable names.
* Use cx_Freeze to make standalone apps.
* Font size 13 on Windows in plot panel.

* Set labelling of second y-axis to the right explicitly, which needs to be
done with newer Matplotlib versions.

* Uses different themes on different operating systems.
* New add_cyclic function used as submitted to Cartopy.

* Works in ipython and jupyter notebooks. Adapted documentation accordingly.
* Added license to documentation.
* Change separator character to unit separator (ASCII 31).
* Print correct coordinates and values on plotting window.
* Set time axis to numpy's datetime64 format.
* Moved from Matplotlib style `seaborn-darkgrid` to `seaborn-dark`.
* Grid is drawn by hand in contour plot. Set automatic grid to False:
`self.axes.grid(False)`.