DHCPv6 decoder update (RFC3646, DNS options)
- Add decoder for option 24 (DOMAIN_LIST)
- Rename option 23 as DNS_SERVERS
- Rename option 24 as DOMAIN_LIST
- In dhcp6opt_print() constify dh6o
Merge pull request #309 from fxlb/master

DHCPv6 decoder update (RFC3646, DNS options)