Currently unused, but planned to provide support for marking individual
language links in the UI, e.g. for featured articles.
+'LanguageSelector': Hook to change the language selector available on a page.
+$out: The output page.
+$cssClassName: CSS class name of the language selector.
+
'LinkBegin': Used when generating internal and interwiki links in
Linker::link(), before processing starts. Return false to skip default
processing and return $ret. See documentation for Linker::link() for details on
&$titleArray: set this to an object to override the default object returned
$res: database result used to create the object
+'TitleExists': Called when determining whether a page exists at a given title.
+$title: The title being tested.
+&$exists: Whether the title exists.
+
'TitleQuickPermissions': Called from Title::checkQuickPermissions to add to
or override the quick permissions check.
$title: The Title object being accessed