[1.7.0] Add versioning to serializer cache

- Make some AttrDef member-variables lazy-loading to save serialization space, clean up others
- Refactor get*Definition() methods

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1116 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/AttrDef/URI/IPv6.php

@@ -13,6 +13,8 @@ class HTMLPurifier_AttrDef_URI_IPv6 extends HTMLPurifier_AttrDef_URI_IPv4
     
     function validate($aIP, $config, &$context) {
         
+        if (!$this->ip4) $this->_loadRegex();
+        
         $original = $aIP;
         
         $hex = '[0-9a-fA-F]';