The Ibft consensus mechanism is responsible for sending a variety of
messages to other validating nodes in the network (provided they have
a point-to-point connection to them).
This change tracks which nodes have connected to the IBFT
subprotocol, and provides the functionality to only transmit messages
to nodes which are also validators.
* Upgrade ethereum reference tests
* Add support for sealEngine: NoProof by skipping PoW validation for ommer headers as well. Production code continues to always use full validation for ommers.
* Add Constantinople to reference test schedules ready for when we enable Constantinople tests.
* Blacklist the new reference tests that are failing while we investigate them.
The MiningCoordinator has been split into common, and ethhash
specific funcationality.
This adversely affects the JSON RPC, in that all mining related
RPCs are now generic based on the type of miner being used.