optimise a list of IPv4/IPv6 prefixes
aggregate6 takes a list of IPv4 and IPv6 prefixes in conventional
format on stdin, and performs two optimisations to attempt to reduce
the length of the prefix list.

The first optimisation is to remove any supplied prefixes which are
superfluous because they are already included in another supplied
prefix. For example, 2001:67c:208c:10::/64 would be removed if
2001:67c:208c::/48 was also supplied.

The second optimisation identifies adjacent prefixes that can
be combined under a single, shorter-length prefix. For example,
2001:67c:208c::/48 and 2001:67c:208d::/48 can be combined into the
single prefix 2001:67c:208c::/47.

Maintainer: Job Snijders <job@openbsd.org>

WWW: https://github.com/job/aggregate6/
