+'ChangesListSpecialPageStructuredFilters': Called to allow extensions to register
+filters for pages inheriting from ChangesListSpecialPage (in core: RecentChanges,
+RecentChangesLinked, and Watchlist). Generally, you will want to construct
+new ChangesListBooleanFilter or ChangesListStringOptionsFilter objects.
+
+When constructing them, you specify which group they belong to. You can reuse
+existing groups (accessed through $special->getFilterGroup), or create your own
+(ChangesListBooleanFilterGroup or ChangesListStringOptionsFilterGroup).
+If you create new groups, you must register them with $special->registerFilterGroup.
+$special: ChangesListSpecialPage instance
+