add support for list of AP connections

- auto select ssid with best signal
 - for debugging enable DEBUG_WIFI_MULTI macro and call Serial.setDebugOutput(true);

change ESP8266WiFiClass::status() return type to wl_status_t

libraries/ESP8266WiFi/src/ESP8266WiFiMulti.h

@@ -0,0 +1,59 @@
+/**
+ *
+ * @file ESP8266WiFiMulti.h
+ * @date 16.05.2015
+ * @author Markus Sattler
+ *
+ * Copyright (c) 2015 Markus Sattler. All rights reserved.
+ * This file is part of the esp8266 core for Arduino environment.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+
+#ifndef WIFICLIENTMULTI_H_
+#define WIFICLIENTMULTI_H_
+
+#include <vector>
+
+//#define DEBUG_WIFI_MULTI(...) os_printf( __VA_ARGS__ )
+
+#ifndef DEBUG_WIFI_MULTI
+#define DEBUG_WIFI_MULTI(...)
+#endif
+
+typedef struct {
+        char * ssid;
+        char * passphrase;
+} WifiAPlist_t;
+
+class ESP8266WiFiMulti {
+    public:
+        ESP8266WiFiMulti();
+        ~ESP8266WiFiMulti();
+
+        bool addAP(const char* ssid, const char *passphrase = NULL);
+
+        wl_status_t run(void);
+
+    private:
+        std::vector<WifiAPlist_t> APlist;
+        bool APlistAdd(const char* ssid, const char *passphrase = NULL);
+        void APlistClean(void);
+
+};
+
+#endif /* WIFICLIENTMULTI_H_ */