Avoid MathText side-effects on Python interpreter
The vtkMatplotlibMathTextUtilities class previously used the vtkPythonInterpreter::Initialize() method to initialize the Python interpreter for matplotlib. Unfortunately, this has side-effects (setting paths, redirecting output) that are not wanted by people who are using the native Python interpreter. This new code first checks if Python is already initialized before calling vtkPythonInterpreter::Initialize().
Closes: #19371 (closed)
Edited by David Gobbi