NewBlockchainReactor returns new reactor instance.

NewBlockPool returns a new BlockPool with the height equal to start.

BlockchainChannel is a channel for blocks and status updates (`BlockStore` height).

BlockchainReactor handles long-term catchup syncing.

BlockPool keeps track of the fast sync peers, block requests and block responses.

BlockRequest stores a block request identified by the block Height and the PeerID responsible for delivering the block.