p2p finish syncing new nodes

[pmesnier]

This is focusing on retrieving the blocks newer than the last irreversible. My assumption is that when a peer sends a notification of blocks, the vector will contain the blocks in order.

Finally the peer needs to collect unblocked signed transactions. I suppose there are on average 1.5 seconds worth of transactions which could still be 10000s of txns.

[pmesnier]

Many of the necessary code changes for the notify/request/supply of "reversible" blocks is already in branch p2p-send-block-summaries, so I a continuing in that source branch.

[pmesnier]

All the code is in, at least as a first pass, but I still see sync failures as described in #421. The failure that is most common occurs when the launcher uses the "star" topology which happens to set up connections to peers except to adjacent ones.

[pmesnier]

The fix is in for the sync test failure reported in #421. Also added a config.ini option: send-whole blocks=[TRUE/false] when false, the net plugin will send block summaries instead of full blocks.

I still lack an effective way to bulk-transfer unblocked signed transactions, although I have some ideas. This is only an issue when the new send-whole-blocks option is set to false and a node needs to sync up with the chain.

I'll make a PR for what's ready now, so this issue will close along with #421 and I'll open a new one to tackle the un-blocked transactions situation.

[pmesnier]

PR #543 addresses this issue