#17 Need list of recently added addresses

[Jeff Ahrenholz]

The router setup for the IETF networks features router
solicitations every few seconds. HIP should be smart
about these IPV6 address add messages coming from
RTNETLINK -- if the address is already on the list,
don't perform another select_preferred_address()
calculation, and suppress messages that would print out
every few seconds for new IPv6 addresses.