Forms implementation for %HTML.Trusted. Some backend changes:

* Added Charsets and Character attribute types
* Fix a heavily recursive form of ContentSets, this allows a content-set
  to include another content-set which includes another content-set, and
  so forth.

Signed-off-by: Edward Z. Yang <edwardzyang@thewritingpot.com>

library/HTMLPurifier/AttrTransform/Textarea.php

@@ -0,0 +1,16 @@
+<?php
+
+/**
+ * Sets height/width defaults for <textarea>
+ */
+class HTMLPurifier_AttrTransform_Textarea extends HTMLPurifier_AttrTransform
+{
+    
+    public function transform($attr, $config, $context) {
+        // Calculated from Firefox
+        if (!isset($attr['cols'])) $attr['cols'] = '22';
+        if (!isset($attr['rows'])) $attr['rows'] = '3';
+        return $attr;
+    }
+    
+}