Split message channels
In short, expired ballot is made even in self mode. So we should split these message channels.
When I run the sebak and push so many payment tx messages with sebak-hot-body,
the EXPIRED ballot is made even though it is self mode.
The result is like this.

There are many errors because of EXPIRED ballot I think.
Since there is one channel to receive messages so if there are too many transactions from client, then ballot and connection messages delayed after transaction messages.
That's why the timeout is occurred.
Therefore we should split these message channels.
As @Geod24 said in meeting, we should split messages from known peers and the others.
Sorry, I misunderstood. https://github.com/bosnet/sebak/blob/master/lib/node/runner/api_node.go#L105
The TransactionMessages from nodes have the other channel with BallotMessage and ConnectMessage.
So the EXPIRED ballots above are not because of one channel.
But still we need the channel splitting(or the other solution) since a bad guy can send huge number of ballots.