Jucs ipv6 rebase

The repo git://github.com/jucs/iodine.git started with a version of iodine from a few years ago, and added IPv6 support.  I'm not sure if these changes are useful, but in order to have a proper look at them I rebased them on top of the commit in yarrick/iodine from which they actually started, with some keywork expansions squashed and some generated files clipped.  The result is the branch jucs-ipv6-rebase in my repo, see above.

It cannot be merged automatically onto the current development tip (there are conflicts and such) but I thought it might be useful to have this information present when adding full IPv6 support.