[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/Context.php

@@ -69,7 +69,7 @@ class HTMLPurifier_Context
      * Loads a series of variables from an associative array
      * @param $context_array Assoc array of variables to load
      */
-    public function loadArray(&$context_array) {
+    public function loadArray($context_array) {
         foreach ($context_array as $key => $discard) {
             $this->register($key, $context_array[$key]);
         }