Added more tests, but there's something fishy; suddenly I'm not getting overflow errors etc.
Added more tests, but there's something fishy; suddenly I'm not getting overflow errors etc.

I suspect that the arithmetically inconvenient types I defined aren't as bad as I'd like
them to be; more work will be required.

tnotstar/pycalcstats,tnotstar/pycalcstats,bmcculley/pycalcstats,bmcculley/pycalcstats