Identify should _replace_ addresses

[Stebalien]

Currently, we add all addresses a peer tells us about using identify. Really, we should replace the addresses we know for the peer as we likely have out-of-date information.

May relate to: #575

[vyzo]

Yes, we need to stop being additive and trust the peer itself.

[Stebalien]

So, this also appears to be affecting autorelay. With autorelay, we push new addresses after we pick a relay. Unfortunately, this means our peers will continue to show both addresses instead of replacing the old ones.

This also explains why we're seeing peers advertising both types of addresses.

[vyzo]

So this should be straightforward, we can simply do SetAddrs in identify instead of AddAddrs.

[vyzo]

Implemented in #599.