[3.1.0] Deprecate addFilter; set up Filter namespace

- Added EXTERNAL dependency config-schema value
- Fix safe bug in Printer_HTMLDefinition
- Fixed broken smoketests

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1669 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/ConfigSchema/Interchange/Directive.php

@@ -67,5 +67,9 @@ class HTMLPurifier_ConfigSchema_Interchange_Directive
      */
     public $deprecatedVersion;
     
+    /**
+     * List of external projects this directive depends on, e.g. array('CSSTidy').
+     */
+    public $external = array();
     
 }