Calculator: ignore probable attempts at hex notation.

This regex overreaches a bit, because query_nowhitespace doesn't
guarantee we'll see word-breaks exactly where we might expect.  This is
sufficient for now, but this triggering needs a general rethink.

Addresses some concerns in issue #517.
Calculator: ignore probable attempts at CIDR notation.

If we get a dotted quad, slash and a number in the range of 0-32, it
seems more likely this is talking about network addresses, than trying
to do a calculation.

I, personally, think it's unlikely we ever should be dealing with dotted
quads, but I want to leave in the possiblity of a pasted-in euro-style
value.

Fixes #541.
Calculator: ignore attempts at subnet notation.

This one is much harder to hit, because the dotted quads must have 3
digits in each of the last 3 positions and they tend to start zero-ing
the mask earlier, but might as well cover this better, too.

Thanks to @mintsoft for the heads-up.
Merge pull request #547 from mwmiller/calc_triggers

Calc triggers