Filter private networks from crawls.

[peterbraden]

This prevents the following scenarios.

(1)

• We crawl a host on a remote network
• That node has a list of nodes that are on it's private network
• We receive these and look for them on the same private address on our unrelated network.

(2)

• Somehow I am dialing myself (address/port) with a same or different id

(3)

• I am dialing someone else, with my ID

[peterbraden]

Had a conversation with Robert and will reconsider this:

• Even if we exclude multiaddresses from the crawl we still need to pass the public keys.
• We therefore need to filter the multiaddresses, rather than the peers.
• Additionally we should have the same exclusion on transport dial.

[robertkiel]

For the dial request, the following will not work:

• dialing localhost:{our_port}
• dialing {our local address}:{our_port}
• dialing our peerId

[peterbraden]

The second two of those are already filtered - I'll add the first.