SConstruct : format system include directories cross-platform
SConstruct : format system include directories cross-platform

- Windows needs /Iinclude.h
- Linux / Mac needs "-isystem include.h"
- both can use CXXFLAGS because we handle the platform differences and don't needs Scons to take care of that
- standardize module configurations to use a dictionary of options that are included in both the main library and the Python module for that library

appleseedhq/cortex,appleseedhq/cortex,appleseedhq/cortex