setup.py build error on macOS 10.13+ #19

Hi, compilation does not work on macOS 10.13+ with error
PythonTextInterp.C:30:10: fatal error: 'Python/errcode.h' file not found #include "Python/errcode.h"

Quick fix was to comment out a few lines around l.30 invmd-python/vmd/vmd_src/src/PythonTextInterp.C:

//#if defined(__APPLE__)
// use the Apple-provided Python framework
//#include "Python/errcode.h"
//#else
#include "errcode.h"
//#endif