add headers for new methods

NTPClient.h

@@ -44,6 +44,21 @@ class NTPClient {
      */
     void setPoolServerName(const char* poolServerName);
   
+    /**
+     * Set time server IP address
+     *
+     * @param poolServerIP
+     */
+    void setPoolServerIP(IPAddress poolServerIP);
+    
+    /**
+     * Set time server domain or IP address
+     *
+     * @param poolServerAddress
+     */
+    void setPoolServerAddress(const char* poolServerAddress);
+    void setPoolServerAddress(IPAddress poolServerAddress);
+
     /**
      * Starts the underlying UDP client with the default local port
      */