'GetIP': modify the ip of the current user (called only once).
&$ip: string holding the ip as determined so far
+'GetLangPreferredVariant': Called in LanguageConverter#getPreferredVariant() to
+ allow fetching the language variant code from cookies or other such
+ alternative storage.
+&$req: language variant from the URL (string) or boolean false if no variant
+ was specified in the URL; the value of this variable comes from
+ LanguageConverter#getURLVariant()
+
'GetLinkColours': modify the CSS class of an array of page links.
$linkcolour_ids: array of prefixed DB keys of the pages linked to,
indexed by page_id.