Fix integer limit symbol includes in Python C extension

INT32_MAX etc was not included correctly
Newer GCC and Clang are permissive enough to accept them but it didn't work on our CentOS 6 image.
Rather than doing C-compatibility includes correctly, I replaced them with std::numeric_limits.

The patch also adds workaround for VC++ where std::numeric_limits does not work in a single particular place of code for some reason.