Move all single-value options outside rules loop
Split processing for IPv4 and IPv6 addresses
Make rule_action_param() ip(6)tables use explicit
Prevent arbitrary namespace switches

For instance, creating an ipv4 rule in an ipv6 interface must be prevented
Also, cache the current namespace to improve performance
Allow independent setting of ipv4 and ipv6 src/dst
Reset namespace stack entering an interface/router

Fix error handling when an illegal change is detected