Feature: The firewall program should have better IPv4 vs IPv6 support.

Feature: The firewall program should have better IPv4 vs IPv6 support.

Add two parameters to explicitly chose between IPv4 and IPv6 (`-4` and `-6`, respectively).
The default behavior is to display both.
This default `firewall show` will now therefore show both IPv4 and IPv6.

Add `(IPv4)` and `(IPv6)` to the output from the `firewall show` command.

When the firewall rules set the tool to either IPv4 or IPv6 but the command line is designating that either IPv4 or IPv6 is specifically enabled or not, then do operate on the tools that are not enabled.
Therefore if the firewall rules have an IPv6 tool (as is the case in the example/default settings for `icmpv6`) and something like `firewall start -4` is used then those IPv6 ruls are ignored.