More Integer Overflow stuff

I think I've said this a billion times, but I'll say it again. No-one has done more research into integer overflow (and underflow, and truncation and signed-ness) issues than my good friend and co-author, David LeBlanc.

So here's the great news - he's updated his very cool (and fast) C++ SafeInt class and written some more words of wisdom.

Here 'tis...