Rename mqtt_topic to default topic

mqtt_sensord/mqtt_sensord.py

@@ -37,8 +37,8 @@ def main():
         client_id = None
 
     mqtt = MQTTClient(mcfg['host'], mcfg['user'], mcfg['password'], client_id)
-    mqtt_topic = mcfg['sensor_topic']
-    print("Connected to", mqtt.host, "with topic", mqtt_topic)
+    default_mqtt_topic = mcfg.get('sensor_topic')
+    print("Connected to", mqtt.host, "with default topic", default_mqtt_topic)
     mqtt.set_callback(sensorlib.Sensor.run_mqtt_callback)
 
     sensors = []
@@ -63,8 +63,8 @@ def main():
             if sensor.HAS_SENSOR_DATA:
                 data = sensor.gen_datapoint()
                 if debug:
-                    print(mqtt_topic, data)
-                mqtt.send_data(mqtt_topic, data)
+                    print(default_mqtt_topic, data)
+                mqtt.send_data(default_mqtt_topic, data)
             if not mqtt.is_async():
                 mqtt.process_mqtt()