MathGL: some optimizations to Qt rework and fixes to JSON compile.
MathGL: some fixes to Qt rework.
MathGl: selecting, using and searching for various Qt versions reworked.
Fix for cmake 3.22 or newer, and .pyc filename version numbering.
Removed Qt4 compilation
Fixes for find_package(MathGL2) and openmp libs
Set OLD policies for SWIG
MathGl-2x: fixes for cmake 3.11+