feat: Add IPv6 support and improve interface display

[chofstede]

This PR updates jmore to support displaying IPv6 addresses alongside IPv4.

Key Changes:

Dual Stack: Now captures inet6 output from netstat (both on host and inside jails).

Config Parsing: Added support for parsing ip6.addr from configuration files.

Filtering: explicit filtering for loopback (::1) and link-local (fe80::) addresses to keep the output clean.

Deduplication: Added sort -u to interface detection to prevent duplicate interface names (e.g., vnet0/vnet0) when an interface has multiple IP families.

This approach is way less invasive than my previous attempt (minimal changes) and keeps compatibility to IPv4-only hosts without any major formatting or logic changes.

Example Output:

root@mail:/usr/local/bin # jmore6
      JAIL JID CPU/% RAM/mb TYPE VER    DIR              IFACE IP(s)                              
 mailstack   1   0.0  343.3 vnet 15.0-R /jails/mailstack vnet0 10.0.0.3/2a01:4f8:1c1c:4d2:8000::3 
   webmail   2   0.0  146.6 vnet 15.0-R /jails/webmail   vnet0 10.0.0.4/2a01:4f8:1c1c:4d2:8000::4 
  imapsync   3   0.0   11.7 vnet 15.0-R /jails/imapsync  vnet0 10.0.0.5/2a01:4f8:1c1c:4d2:8000::5 
    client   4   0.0   11.7 vnet 15.0-R /jails/client    vnet0 2a01:4f8:1c1c:4d2:8000::6          

[vermaden]

Thank You for this addon - I will find some time next week to seat on it.