add basic WPS function

libraries/ESP8266WiFi/src/ESP8266WiFi.h

@@ -109,7 +109,7 @@ public:
      *
      * return: one value of wl_status_t enum
      */
-    int disconnect(void);
+    int disconnect(bool wifioff = false);
 
     /*
      * Get the station interface MAC address.
@@ -313,6 +313,13 @@ public:
     bool hostname(const char* aHostname);
     bool hostname(String aHostname);
 
+
+    /**
+     * WPS config
+     * so far only WPS_TYPE_PBC is supported (SDK 1.2.0)
+     */
+    bool beginWPSConfig(void);
+
     /*
      * Output WiFi settings to an object derived from Print interface (like Serial).
      *