TalkMaster: Switch master if dialed M is secondary

When connecting to a master node, the client needs to try a different
master if the initially tried one is a secondary master node. This
statement wasn't implemented yet before this patch and therefore it was
good luck if the initally tried master was the primary one - and the
connection worked - or if it was a secondary master - and the client
got stuck in re-trying the same node forever. This patch makes NEO/go
usage with clusters of more than one master therefore much more stable.

go/neo/mastered.go

@@ -130,8 +130,14 @@ func (node *_MasteredNode) TalkMaster(ctx context.Context, f func(context.Contex
 		if errors.Is(err, cmdShutdown) {
 			return err // M commands to shutdown
 		}
+
+		var notPrimaryMaster *proto.NotPrimaryMaster
+		if errors.As(err, &notPrimaryMaster) {
+			primary := notPrimaryMaster.KnownMasterList[notPrimaryMaster.Primary]
+			node.MasterAddr = fmt.Sprintf("[%s]:%v", primary.Host, primary.Port)
+		}
+
 		// TODO if err == "reject identification / protocol error" -> shutdown client?
-		// TODO if err == "not a primary" -> try redirected address
 
 		// exit on cancel / throttle reconnecting
 		select {