MDL-9151 HTML Purifier cleaning support - enable switch is in experimental section

MDL-9435 Reviewved url cleaning in redirect()

lib/htmlpurifier/HTMLPurifier/Strategy.php

@@ -0,0 +1,33 @@
+<?php
+
+/**
+ * Supertype for classes that define a strategy for modifying/purifying tokens.
+ * 
+ * While HTMLPurifier's core purpose is fixing HTML into something proper, 
+ * strategies provide plug points for extra configuration or even extra
+ * features, such as custom tags, custom parsing of text, etc.
+ */
+
+HTMLPurifier_ConfigSchema::define(
+    'Core', 'EscapeInvalidTags', false, 'bool',
+    'When true, invalid tags will be written back to the document as plain '.
+    'text.  Otherwise, they are silently dropped.'
+);
+ 
+class HTMLPurifier_Strategy
+{
+    
+    /**
+     * Executes the strategy on the tokens.
+     * 
+     * @param $tokens Array of HTMLPurifier_Token objects to be operated on.
+     * @param $config Configuration options
+     * @returns Processed array of token objects.
+     */
+    function execute($tokens, $config, &$context) {
+        trigger_error('Cannot call abstract function', E_USER_ERROR);
+    }
+    
+}
+
+?>