With these changes, a container can have more then one veth-pair. This allows for example to have LAN and DMZ as bridges on the host and add dedicated containers for proxies, ipv4-firewall and ipv6-firewall. Or to have a bridge for normal WAN, one bridge for administration and one bridge for customer-internal communication. So that web-server containers can be reached from outside per http, from the management via ssh and can talk to their database via the customer network.
The scripts to set up the containers are now rendered several times instead of just one template. The scripts now contain per-container code to configure the extra veth interfaces. The default template without support for extra-veths is still rendered for the imperative containers.
Also a test is there to see if extra veths can be placed into host-bridges or can be reached via routing.
