State transfer

[sergefdrv]

This pull request resolves #11. Tested on chat demo with the following patch:

diff --git a/pkg/iss/iss.go b/pkg/iss/iss.go
index 68d38ed..ae67d31 100644
--- a/pkg/iss/iss.go
+++ b/pkg/iss/iss.go
@@ -665,6 +665,9 @@ func (iss *ISS) applyMessageReceived(messageReceived *eventpb.MessageReceived) *
 	case *isspb.ISSMessage_StableCheckpoint:
 		return iss.applyStableCheckpointMessage(msg.StableCheckpoint, from)
 	case *isspb.ISSMessage_Sb:
+		if iss.ownID == t.NodeID("1") {
+			return &events.EventList{}
+		}
 		return iss.applySBMessage(msg.Sb, from)
 	case *isspb.ISSMessage_RetransmitRequests:
 		return iss.applyRetransmitRequestsMessage(msg.RetransmitRequests, from)

Closes consensus-shipyard/consensuslab#69
Closes consensus-shipyard/consensuslab#62

[matejpavlovic]

Very nice! Found just a few typos and have one question.

[sergefdrv]

Summary of changes: fixed typos

[sergefdrv]

Summary of change: removed deferring of epoch instance activation upon restoring state snapshot