Remove unnecessary use of static_cast<int>

git-svn-id: https://cantera.googlecode.com/svn/cantera/trunk@2712 02a645c2-efd0-11dd-984d-ab748d24aa7e
[SCons] Use SCons to compile the Cython extension

Fixes issues with mismatched compilers between the Cython extension and the
cantera library, especially on OS X. Improves build dependency resolution to
eliminate unnecessary recompilation of _cantera.cpp.

git-svn-id: https://cantera.googlecode.com/svn/cantera/trunk@2713 02a645c2-efd0-11dd-984d-ab748d24aa7e