Network: Send State when peer is behind and there are no new transactions

[gerardsn]

reflects latest protocol update, see nuts-foundation/nuts-specification#189

If the Gossip does not result in the same XOR as its peer, the node now always makes an attempt at resolving their differences.

[reinkrul]

Might be good to add an integration test for this? I suspect we could test this by starting one node which adds lots of TXs, then start a second node?

On the other hand, this really sounds like the "bootstrap/new node" scenario, which is probably already tested in the integration test?

[gerardsn]

Might be good to add an integration test for this? I suspect we could test this by starting one node which adds lots of TXs, then start a second node?

On the other hand, this really sounds like the "bootstrap/new node" scenario, which is probably already tested in the integration test?

This specific change solves the case where a slow node is always behind and publishes a new transaction, but somehow the gossip didn't get through. In the old situation the peer would never be able to get its transaction out, but now it does. Added an integration test for this.