[Python-3000] C API for ints and strings

["Martin v. Löwis"]

> Interesting, I didn't look at the code (obviously), but my
> understanding was that it was only positive integers below 100.

See NSMALLPOSINTS and NSMALLNEGINTS. It's 257 positive ints since
r42552, contributed through bugs.python.org/1436243.

Regards,
Martin