This adds support for IPv6, by giving all `start.sh` scripts an `-6` argument, that causes a dualstack configuration to be loaded.
Each individual docker-compose file has been split out. Now, each file no longer defines any networking. Instead, one of two networking fragments is expected to be merged in.
When starting Openfire, a Hazelcast configuration option is passed through to the Openfire process to denote preference for IPv4 or IPv6. This passing through depends on the change in Openfire, that is introduced by 2634d4a83a
Minor other changes have been applied, that mostly make the start scripts more consistent amongst each-other.
fixes#61
Guus der Kinderen
Dan Caseley