fixed V::humanFileSize to static

SE/se-lib/V.php

@@ -416,7 +416,7 @@ EOF';
 		return $arr;
 	}
 
-	public function humanFileSize($bytes) {
+	public static function humanFileSize($bytes) {
 		$bytes = intval($bytes);
 		$arBytes = array(
 			0 => array("UNIT" => "TB", "VALUE" => pow(1024, 4)),