fix bug #343

add __attribute__ to printf functions for better compiler warning handling.
remove ICACHE_FLASH_ATTR, all cpp files are automatic in FLASH (ld script)

libraries/ESP8266WiFi/src/ESP8266WiFi.h

@@ -116,6 +116,7 @@ public:
      */
     uint8_t* softAPmacAddress(uint8_t* mac);
     String softAPmacAddress(void);
+
     /*
      * Get the station interface IP address.
      *