add support for routing domains to the "show ip" command

[smytht]

nsh(p)/show ip Address Interface RDomain Type 10.0.2.15 em0 0 dhcp 10.10.10.10 em1 200 static 127.0.0.1 lo0 0 static ::1 lo0 0 static fe80:4::1 lo0 0 link-local nsh(p)/show inet Address Interface RDomain Type 10.0.2.15 em0 0 dhcp 10.10.10.10 em1 200 static 127.0.0.1 lo0 0 static nsh(p)/show inet6 Address Interface RDomain Type ::1 lo0 0 static fe80:4::1 lo0 0 link-local