The command takes as input address lists in the PeerGuardian P2P plaintext format (see https://en.wikipedia.org/wiki/PeerGuardian#P2P%20plaintext%20format), where each line is in the following format
RangeName:aaa.bbb.ccc.ddd-eee.fff.ggg.hhh
where aaa.bbb.ccc.ddd-eee.fff.ggg.hhh represents a continuous range of IP addresses. Those range are not always describing a CIDR network so we may have to split it in a set of netmaskable entities.
We convert that to a list of ipaddress/netmask, one per line, suitable to use with OpenBSD's pfctl.
To build the tool, just issue the command "make iplistransform".