fix because of SoftwareSerial API change (esp8266#6635)

Author: d-a-v

libraries/ESP8266WiFi/examples/WiFiTelnetToSerial/WiFiTelnetToSerial.ino

@@ -85,8 +85,9 @@ void setup() {
   Serial.swap();
   // Hardware serial is now on RX:GPIO13 TX:GPIO15
   // use SoftwareSerial on regular RX(3)/TX(1) for logging
-  logger = new SoftwareSerial(3, 1);
-  logger->begin(BAUD_LOGGER);
+  logger = new SoftwareSerial();
+  logger->begin(BAUD_LOGGER, 3, 1);
+  logger->enableIntTx(false);
   logger->println("\n\nUsing SoftwareSerial for logging");
 #else
   logger->begin(BAUD_LOGGER);