Standardise LAN net display

On the main firewall rules multi-rule display it shows "LAN net" "WAN net" etc. But on the edit screen it shows "LAN subnet" "WAN subnet" etc. Make the edit screen have the same text as the main screen - this has ben a source of enough little questions/queries on the forum.
Standardise LAN net display
Standardise LAN net display
Merge pull request #902 from phil-davis/master

Standardise LAN net display