* Add function to update a dict recursively with other dicts
* Refactor Axes and NumberPlane
* Fix NumberLine's rotation
* Rotate NumberLine just before adding numbers
* More refactoring
* Add graphical unit test to NumberPlane
* More cleanup and fix range attributes issue(#840)
* Remove overlooked print statements and run black
* Make graphical unit test of NumberPlane more robust
* Shift z_axis to XY-plane's origin and minor refactor in its rotation
* Apply review suggestions