Move header to include directory

include/wlan.h

@@ -0,0 +1,20 @@
+#ifndef WLAN_H
+#define WLAN_H
+
+#include <ESP8266WiFi.h>
+#include <PubSubClient.h>
+
+const int SLEEP_TIME = 900000000;
+const int WIFI_TIMEOUT = 10000;
+
+void initial_connection();
+void connect_wlan(const int max_retries);
+void connect_mqtt(PubSubClient &client, const char *device_id,
+                  const char *topic);
+void disconnect_mqtt(PubSubClient &client, const char *topic);
+size_t construct_json(float *data, char *buffer, int buffer_size);
+void mqtt_transfer(PubSubClient &client, const char *device_id,
+                   const char *topic, float *data);
+void enter_deep_sleep(bool wifi_timeout);
+
+#endif /* WLAN_H */