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This will mitigate the fd explosion, but slow down dials majorly
as any peer with more addresses than the rate limit will have
to wait a whole dial timeout (~15s)

This addr manager should seriously help with the addrsplosion
problem.

Network now signals when it successfully listens on some address
or when an address shuts down. This will be used to establish and
close nat port mappings. It could also be used to notify peers
of address changes.

+ fixed race

This commit turns all dial logs into log.Events.

Everything's great except for one problem:
The LoggableMap I'm using does not print out things
correctly. I gave it peer.IDs, and Multiaddrs
and both got logged as nothing `{}` (didn't even call
their String() methods!) So, for now, this function
encodes it when called... This is wrong and should be
fixed before being merged in. Otherwise we  will be
constantly encoding peer.IDs and Multiaddrs without
needing to.

@briantigerchow how do you suggest doing this?
I don't know my way around your Loggable.

This commit cleans up the reuse port setup, and fixes a problem:
make sure to filter addrs out that we simply cannot dial with
(e.g. loopback -> non-loopback, or linklocal -> nonlinklocal)

this is actually pretty important in case some peers end
up changing addrs, so others dont fail dialing simply for
picking the wrong addr to start with.

This commit introduces a backoff when failing to dial
peers. It makes everything much faster.

* filtering InterfaceListenAddresses(s) instead
* return error if for loops skip
* large dial timeout

This adds two checks after a successful conn.Dial
* if the remote peer is not who we wanted, close conn
* if the remove peer is outselves, close conn

(the second is redundant, but the codebase may evolve to
end up disabling the first check, so keeping the second
in place helps)

note:
Loopback addresses are actually sent out (they _have to be_,
in cases where there are >1 node in the same machine), so
many times when trying connections, nodes end up dialing
themselves.

The net package is the next to move. It will be massaged
a bit still to fix the Network / "NetworkBackend" conflict.