initialize if not already initialized

remove gateway fs

add gateway server

fixes breakages:
  - peer.Peer -> peer.ID
  - peer.X -> peer.PeerInfo
  - netmsg -> p2p streams

off by one error seeking to end of single block file

AddrSplosion -- Partie Deux Avec Vengeance

Implement io.Seeker on unixio.DAGReader

dropped down log.Errors

misc user-friendliness fixes

CLI changes

NAT-Lite

should be returning false.

Exposing the NAT to the core is unnecessary. The Host can take
care of it. If a need emerges, we can address it then.

- allow retrieving addresses
- allow notifications on mapping changes
- allow lifecycle mgmt (future commit will manage it)