* Add test to CMakeLists.txt to verify wxPython is installed when
  KICAD_SCRIPTING_WXPYTHON=ON.
* Add test to make sure wxPython version major and minor numbers match
  the version of wxWidgets found.
* Add code to set the correct version of wxPython to the python scripting
  initialization code.
* Minor code simplification in Pcbnew KIFACE main window creation.