[3.1.1] Allow injectors to be specified by modules.

- Make method for URI implemented
- Split out checkNeeded in Injector from prepare

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1779 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/HTMLModule.php

@@ -71,6 +71,14 @@ class HTMLPurifier_HTMLModule
      */
     public $info_attr_transform_post = array();
     
+    /**
+     * List of HTMLPurifier_Injector to be performed during well-formedness fixing.
+     * An injector will only be invoked if all of it's pre-requisites are met;
+     * if an injector fails setup, there will be no error; it will simply be
+     * silently disabled.
+     */
+    public $info_injector = array();
+    
     /**
      * Boolean flag that indicates whether or not getChildDef is implemented.
      * For optimization reasons: may save a call to a function. Be sure