Added MQTT client, better speaker handling, fixed bug in FTP server, ...

include/mqtt_client.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "config.h"
+#include <PubSubClient.h>
+#include <ESP8266WiFi.h>
+
+class MQTTClient {
+private:
+	WiFiClient* _wifi_client;
+	PubSubClient* _mqtt;
+	unsigned long _last_reconnect_attempt;
+	void _reconnect();
+public:
+	MQTTClient();
+	void loop();
+	void publish_status(String s);
+	void publish_rfid_uid(uint32_t uid);
+};