[SCons] Fix simultaneous compilation of Python 2 and Python 3 modules
[SCons] Fix simultaneous compilation of Python 2 and Python 3 modules

Use separate SCons Environments so the 'py_include_dirs' variable (which
contains the Numpy include directory) can be distinct for each Python module.

git-svn-id: e76dbe14710aecee1ad27675521492cea2578c83@2710 02a645c2-efd0-11dd-984d-ab748d24aa7e

Cantera/cantera-svn,Cantera/cantera-svn,Cantera/cantera-svn,Cantera/cantera-svn,Cantera/cantera-svn,Cantera/cantera-svn