Fix PHP 5.0 and other early version compatibility by removing use of __toString

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1629 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/ConfigSchema/Interchange/Id.php

@@ -13,7 +13,11 @@ class HTMLPurifier_ConfigSchema_Interchange_Id
         $this->directive = $directive;
     }
     
-    public function __toString() {
+    /**
+     * @warning This is NOT magic, to ensure that people don't abuse SPL and
+     *          cause problems for PHP 5.0 support.
+     */
+    public function toString() {
         return $this->namespace . '.' . $this->directive;
     }