$index: Integer; the index of the namespace being checked.
&$result: Boolean; whether MediaWiki currently thinks that pages in this
namespace are movable. Hooks may change this value to override the return
- value of MWNamespace::isMovable().
+ value of NamespaceInfo::isMovable().
'NewDifferenceEngine': Called when a new DifferenceEngine object is made
$title: the diff page title (nullable)