Use constant xmpp.NoHistory instead of "0"

For a better readability.

go-sendxmpp.go

@@ -421,7 +421,7 @@ func main() {
 			if *flagMUCPassword != "" {
 				dummyTime := time.Now()
 				_, err = client.JoinProtectedMUC(recipient, *flagResource,
-					*flagMUCPassword, 0, 0, &dummyTime)
+					*flagMUCPassword, xmpp.NoHistory, 0, &dummyTime)
 			} else {
 				_, err = client.JoinMUCNoHistory(recipient, *flagResource)
 			}
@@ -492,7 +492,7 @@ func main() {
 			if *flagMUCPassword != "" {
 				dummyTime := time.Now()
 				_, err = client.JoinProtectedMUC(recipient, *flagResource,
-					*flagMUCPassword, 0, 0, &dummyTime)
+					*flagMUCPassword, xmpp.NoHistory, 0, &dummyTime)
 			} else {
 				_, err = client.JoinMUCNoHistory(recipient, *flagResource)
 			}