New creates an Ethereum backend for NeatCon core engine.

So we can control the DefaultDir.

ErrNoPrivValidator is returned if private validator is not set during the start of the node.

ErrStartedEngine is returned if the engine is already started.

ErrStoppedEngine is returned if the engine is stopped.

ErrUnauthorizedAddress is returned when given address cannot be found in current validator set.

Not exposed by neatio.