- previously there was no way to override this value and ipsets would stop being updated when full (Hash is full, cannot add more elements)
- preserve ipset's default value of 65536
- update tests
- Closes#3549
- better check mechanism (using `-C`, option `--check` is available long time);
- additionally iptables-ipset is a common action for iptables-ipset-proto6-* now (which become obsolete now);
- many features of different iptables actions are combinable as single chain/rule (can be supplied to action as parameters);
- tests adjusted.