[3.0.0] Convert all $context calls away from references

- Update TODO list
- URISchemeRegistry doesn't return a reference for instance anymore, should do the same for other singletons

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1477 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/LanguageFactory.php

@@ -89,7 +89,7 @@ class HTMLPurifier_LanguageFactory
      * @param $config Instance of HTMLPurifier_Config
      * @param $context Instance of HTMLPurifier_Context
      */
-    public function create($config, &$context) {
+    public function create($config, $context) {
         
         // validate language code
         $code = $this->validator->validate(