Fix multiple PHP warnings

resources/classes/xml.php

@@ -1,9 +1,14 @@
 <?php
 
+	/**
+	 * xml class
+	 */
 	class xml {
 
 		/**
 		 * Escapes xml special characters to html entities and sanitze switch special chars.
+		 * @param  mixed $string
+		 * @return void
 		 */
 		static function sanitize($string) {
 			$string = preg_replace('/\$\{[^}]+\}/', '', $string);