[4o6] changed packet4o6 receiving order
[4o6] move dhcp4o6_ipc.{c,hh} to lib/dhcpsrv/
[4o6] Improve BaseIPC::open()
[4o6] remove&rename current() in dhcp4o6_ipc
[4o6] update copyright date
[4o6] changed exception&comment in dhcp4o6_ipc
[4o6] move dhcp4o6_ipc_unittest to dhcpsrv/