ping6 and other tool6 awkwardness

[Nikos Mavrogiannopoulos]

While working for an updated ipcalc to support ipv6 transparently, I
figured we have more tools which are not IPv6-ready and awkwardly
provide an additional tool with a -6 suffix, supposedly for separate
IPv6 support. That looks like a relic of the past, we still drag. IPv6
support should be transparent in programs (fortunately we don't have
ssh6). Any objection to fill bugs to merge the following tools with
their ipv4 equivalent?

ping6, geoiplookup6, tracepath6, traceroute6

[0]. https://github.com/nmav/ipcalc