Added support for City Network to Dynamic DNS.

City Network is a Swedish web hosting company.
They provide a dynamic DNS service for their customers.
This service uses the dyndns2 protocol.
Make sure automatic rules are created even if mode is not set, ticket #2416
Add subnet to 0.0.0.0 otherwise it's not added to table, ticket #2416
Add an option to return outbound NAT automatic to nat hosts with description, ticket #2416
Add gettext() to recently added strings
Use the same code to automatically create outbound NAT rules when mode change to manual, ticket #2416
Try to detect already automatically created outbound NAT rules and avoid duplicating them. Also automatically create rules when switching from hybrid to manual. Ticket #2416
Fix a wrong } left on my last commit
Improve text on outbound NAT page to reflect last changes, it should fix #2416
Fix whitespaces and indent
Fix whitespaces and indent
We do not need 2 variables to do the same thing, simplify it a bit
Add hability to insert after, reorder, batch delete and enable/disable to 1:1 NAT rules. It fixes #3327
Don't flush interface cache on each call of the function when looping through all gateways.
Fix an issue that changes wrong gateway entry when items are hidden
Merge pull request #857 from Wraul/add_city_network_dyndns

Added support for City Network to Dynamic DNS.
FreeBSD 10 pf does not have a limit for table entries
Fix #3331. Set interface subnet as destination when VIP is in the same subnet, otherwise use VIP subnet instead of IP address
Remove maximumtables even from the GUI since there is no option
Add DHCP without gateway capability