Provide Python visualization functions #548
Description
The current visualization workflow with VTK and Paraview is very flexible and powerful, but it requires a certain effort (the user needs to install Paraview, and learn how to use it). In order to lower this barrier, we should provide simple visualization functions in 2D and 3D using Matplotlib and PyVista. This would allow the user to do everything (simulation and visualization) from the same Python interpreter.