[1.7.0] Add unit test for AttrCollections

- Fixed bug where recursive attribute collections would result in infinite loop
- Fixed bug with deep inclusions in attribute collections
- Reset doctype object if HTML or Attr is changed
- Add accessor functions to AttrTypes, unit tested class

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1077 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/Config.php

@@ -168,9 +168,13 @@ class HTMLPurifier_Config
             return;
         }
         $this->conf[$namespace][$key] = $value;
+        
+        // reset definitions if the directives they depend on changed
+        // this is a very costly process, so it's discouraged 
+        // with finalization
         if ($namespace == 'HTML' || $namespace == 'Attr') {
-            // reset HTML definition if relevant attributes changed
             $this->html_definition = null;
+            $this->doctype = null;
         }
         if ($namespace == 'CSS') {
             $this->css_definition = null;