[3.1.0] More PHP4->PHP5 conversions, notably reference removal of most methods that return objects

- Removed HTMLPurifier_Error
- Documentation updates
- Removed more copy() methods in favor of clone
- HTMLPurifier::getInstance() to HTMLPurifier::instance()
- Fix InterchangeBuilder to use HTMLPURIFIER_PREFIX

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1689 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/Token.php

@@ -14,14 +14,6 @@ class HTMLPurifier_Token {
      */
     public $armor = array();
     
-    /**
-     * Copies the tag into a new one (clone substitute).
-     * @return Copied token
-     */
-    public function copy() {
-        return unserialize(serialize($this));
-    }
-    
     public function __get($n) {
       if ($n === 'type') {
         trigger_error('Deprecated type property called; use instanceof', E_USER_NOTICE);