Sort IP List

[hh]

Remains to remark that the upcoming standard IPv6
with its text representations
(Section 2.2 of https://tools.ietf.org/html/rfc4291)
will require more detailed methods,
both for number base conversion and for item sorts/cosorts
(the items are hex numbers ...)

@Bernd
Depending on the function an inline computation (as Alex denoted)
may be even faster than the private function calls?
Here, with IPv4 addresses, it is faster.