$title: An optional title object used to links to sections. Can be null.
$local: Boolean indicating whether section links should refer to local page.
+'GalleryGetModes': Get list of classes that can render different modes of a
+ gallery
+$modeArray: An associative array mapping mode names to classes that implement
+ that mode. It is expected all registered classes are a subclass of
+ ImageGalleryBase.
+
'GetAutoPromoteGroups': When determining which autopromote groups a user is
entitled to be in.
&$user: user to promote.