Usage example err, and filtering results

Hey, just to highlight that the README example needs an update after the `--ipv6` etc. opts became reverse IP lookups (as per `commit: 2bf0010`).

Further to that, was there a reason to deprecate them as filters? ...guess you could just grep instead? Attached opt. to select an IP type again, seemed trivial enough to reimplement.. but maybe I'm missing the point o_0 ??

Adam