revision of the zone configuration (zoneconf.cgi)

Hi Leo,

a few months ago Florian Bührle implemented the possibility of editing the zone configuration in the web-if. Unfortunately it is a bit confusing and suggestions for improvement could not be implemented until now.

In my opinion it would be good if you could see at a glance which NIC is a part of which zone.

I have attached two pictures. One that shows the actual state and one that shows a possible improvement.

I saw your last patch on the list and thought you might want to take on this task. What is your opinion?

- Daniel