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This addr manager should seriously help with the addrsplosion
problem.

The separation of work in the p2p pkg is as follows:

- net implements the Swarm and connectivity
- protocol has muxer and header protocols
- host implements protocol muxing + services
- identify took over handshake completely! yay.
- p2p package works as a whole

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