Proposal by @milosevic.

Input/Ouput queues

Introduce bounded input / output queues

These queues exist right now in the form of MConnection#sendQueue and Reactor#Receive. Receive is ok. Testing requires setting up the whole consensus and not easy. Tracking of what's been send again is hard.

Move mempool txs into consensus

Combining with ^^, tx can be treated as any other incoming message. When a client sends a tx, we call mempool#CheckTx (which itself calls app) and, if CheckTx passes, we send it to consensus queue.

Handle votes in parallel

to speed up consensus. Right not we're processing them sequencially case mi = <-cs.peerMsgQueue