Update to KivyMD 2.0.0 (WIP, incomplete, do not merge)

[unelsson]

This PR is a hack that allows the basic use of KivyMD 2.0.0. The purpose is to create a working version with minimum effort possible.

What needs to be done before merging:

• check that NavigationLayout -> MDNavigationLayout is the proper way
• update the checkbox color properly (not just force "red")
• kivyutils import BaseFabButton and BaseButton, but only BaseFabButton is used
• check what SizedButton should actually do
• fix whatever is causing [Clock ] Warning, too much iteration done before the next frame.
• fix the issues of drawing SizedButton, including the text not drawn to correct position