Added initial Melody Playback Ability

Now, controlled via MQTT a Playback of a melody can Start, Stop, Pause 
etc. 

Settings like speed, total duration, pauses etc can be set.

build/sketch/ESP32_Utils_MQTT_Async.hpp

@@ -0,0 +1,89 @@
+#line 1 "C:\\Users\\espi_\\Documents\\Arduino\\vesper\\ESP32_Utils_MQTT_Async.hpp"
+#pragma once
+
+TimerHandle_t mqttReconnectTimer;
+TimerHandle_t wifiReconnectTimer;
+
+void ConnectToMqtt()
+{
+	Serial.println("Connecting to MQTT...");
+	mqttClient.connect();
+}
+
+void WiFiEvent(WiFiEvent_t event)
+{
+	Serial.printf("[WiFi-event] event: %d\n", event);
+	switch(event)
+	{
+	case ARDUINO_EVENT_WIFI_STA_GOT_IP:
+		Serial.println("WiFi connected");
+		Serial.println("IP address: ");
+		Serial.println(WiFi.localIP());
+		ConnectToMqtt();
+		break;
+	case ARDUINO_EVENT_WIFI_STA_DISCONNECTED:
+		Serial.println("WiFi lost connection");
+		xTimerStop(mqttReconnectTimer, 0); // ensure we don't reconnect to MQTT while reconnecting to Wi-Fi
+		xTimerStart(wifiReconnectTimer, 0);
+		break;
+	}
+}
+
+void OnMqttConnect(bool sessionPresent)
+{
+	Serial.println("Connected to MQTT.");
+	Serial.print("Session present: ");
+	Serial.println(sessionPresent);
+	SuscribeMqtt();
+}
+
+void OnMqttDisconnect(AsyncMqttClientDisconnectReason reason)
+{
+	Serial.println("Disconnected from MQTT.");
+
+	if(WiFi.isConnected())
+	{
+		xTimerStart(mqttReconnectTimer, 0);
+	}
+}
+
+void OnMqttSubscribe(uint16_t packetId, uint8_t qos)
+{
+	Serial.println("Subscribe acknowledged.");
+	Serial.print("  packetId: ");
+	Serial.println(packetId);
+	Serial.print("  qos: ");
+	Serial.println(qos);
+}
+
+void OnMqttUnsubscribe(uint16_t packetId)
+{
+	Serial.println("Unsubscribe acknowledged.");
+	Serial.print("  packetId: ");
+	Serial.println(packetId);
+}
+
+void OnMqttPublish(uint16_t packetId)
+{
+	Serial.println("Publish acknowledged.");
+	Serial.print("  packetId: ");
+	Serial.println(packetId);
+}
+
+void InitMqtt()
+{
+	mqttReconnectTimer = xTimerCreate("mqttTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(ConnectToMqtt));
+	wifiReconnectTimer = xTimerCreate("wifiTimer", pdMS_TO_TICKS(5000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(ConnectWiFi_STA));
+
+	mqttClient.onConnect(OnMqttConnect);
+	mqttClient.onDisconnect(OnMqttDisconnect);
+
+	mqttClient.onSubscribe(OnMqttSubscribe);
+	mqttClient.onUnsubscribe(OnMqttUnsubscribe);
+
+	mqttClient.onMessage(OnMqttReceived);
+	mqttClient.onPublish(OnMqttPublish);
+
+	mqttClient.setServer(MQTT_HOST, MQTT_PORT);
+	mqttClient.setCredentials(MQTT_USER, MQTT_PASS);
+}