Consensus::startRound

Kick-off the next round of consensus.

void
startRound(
    NetClock::time_point const& now,
    typename Ledger_t::ID const& prevLedgerID,
    Ledger_t prevLedger,
    bool proposing);

Called by the client code to start each round of consensus.

Name	Description
`now`	The network adjusted time
`prevLedgerID`	the ID of the last ledger
`prevLedger`	The last ledger
`proposing`	Whether we want to send proposals to peers this round.

prevLedgerID is not required to the ID of prevLedger since the ID may be known locally before the contents of the ledger arrive