Moved wfSpecialList() to Language::specialList() so that it can be used in the contex...

Moved wfSpecialList() to Language::specialList() so that it can be used in the context of special pages instead of relying unconditionally of $wgLang. Updated all calls in core and added a @deprecated comment to wfSpecialList() but not a wfDeprecated() call since it's still used in SiteMatrix and StalePages extensions.