Set log to trace

`CalculateNextEpoch` should set `SendEpoch` instead of cumulating it.

node/node.go

@@ -182,7 +182,7 @@ func (n *Node) Start(duration time.Duration) {
 				n.logger.Info("Epoch processing stopped")
 				return
 			default:
-				n.logger.Debug("Epoch processing", zap.String("node", hex.EncodeToString(n.ID[:4])), zap.Int64("epoch", n.epoch))
+				n.logger.Trace("Epoch processing", zap.String("node", hex.EncodeToString(n.ID[:4])), zap.Int64("epoch", n.epoch))
 				time.Sleep(duration)
 				err := n.sendMessages()
 				if err != nil {
@@ -545,7 +545,7 @@ func (n *Node) insertSyncState(groupID *state.GroupID, messageID state.MessageID
 
 func (n *Node) updateSendEpoch(s state.State) state.State {
 	s.SendCount += 1
-	s.SendEpoch += n.nextEpoch(s.SendCount, n.epoch)
+	s.SendEpoch = n.nextEpoch(s.SendCount, n.epoch)
 	return s
 }