allow page titles to be enumerated even when they are not guessable.
* (bug 32616) action=ajax requests were dispatched to the relevant internal functions without any read permission checks being done. This could lead to data leakage on private wikis.
* This replaces OuputPage::loginToUse() functionnality, made it simply throw a PermissionsEror exception and updated all calls in core
* Same for the check in SpecialUpload::execute(), EditPage::userNotLoggedInPage() and EditPage::noCreatePermission()
* Throw the same exception in EditPage::attemptSave() whether the user is logged in or not and let OuputPage::showPermissionsErrorPage() decide which message to display
* Replaced call to deprecated OutputPage::blockedPage() in SpecialUpload
* Displayed messages are the same as now, except the title is always "loginreqtitle"
* 'nocreatetitle' and 'uploadnologin' messages are still used by extensions, so I kept them, but the message 'whitelistedittitle' is not used anymore and has been removed
* PermissionsError now calls OutputPage::showPermissionsErrorPage() to display the error (this is needed to make the item above work correctly)
* Removed the override of the HTML title in OutputPage::showPermissionsErrorPage() so that it shows "Permission errors - Sitename" instead of simply "Permission errors" for consistency with the other things
* Pass the error array returned by Title::getUserPermissionsErrors() to PermissionsError where available
* Converted direct calls to OutputPage::showPermissionsErrorPage() to throw an PermissionsError error instead
* Added 'action-rollback' message that will be displayed when accessing action=rollback without sufficient rights
* Changed getRestriction() in subclasses of Action to return null when they previously returned 'read' so that user rights can be check with Title::getUserPermissionsErrors()
* Reordered checks to do first user rights, then block (if needed) and finally read only (also if needed) so that users don't think the error is temporary when they both don't have right and the database is locked
* Removed OutputPage::setPageTitleMsg() and OutputPage::setHTMLTitleMsg() and make OutputPage::setPageTitle() and OutputPage::setHTMLTitle() accept a Message object
* Updated core calls (including some that I missed last time because of non-matching case)
* Added Message::setContext() and use it in RequestContext so that I don't need to duplicate the call in OutputPage
* Yes, I'm calling $this->msg() on places and then setting the context one more time in OutputPage::setPageTitle() or OutputPage::setHTMLTitle(), but at least I won't be confused about which objects $
* Simply use getLang() instead of getContext()->getLang() now that this method exists
* Also changed addWikiMsgArray() to use a Message object with addWikiText() for the parse operation; removed its $options parameter, no caller was using it
* ParserOptions::getUserLang() will still return a string for compatibility, added ParserOptions::getUserLangObj() to get the object
* Added ParserOptions::newFromUserAndLang() and ParserOptions::newFromContext() to easily get a ParserOptions object when a context is available or when someone wants to force the language
* Updated OutputPage and Preferences to use newFromContext() and WikiPage to use newFromUserAndLang()
* ParserOptions::setUserLang() still accepts either a string or a Language object, but changed the calls to pass an object instead of a string
* Changed Parser::getFunctionLang() to return the Language object from ParserOptions when parsing interface messages rather than $wgLang directly and updated the documentation to say that $wgLang should not be used directly (as $wgUser, $wgTitle and $wgRequest)
* to make the output page specific mw.config map extendable.
* fixes (bug 31233) Make OutputPage's mw.config array extendable internally instead of hard coded
* fixes weird unfinished comment from r61690
* Made variant tabs hidden on special pages (has no or sometimes wrong/inconsistent effect there; plus it's mainly in the user language)
* Made redirects be in content language again (remove from Title->getPageLanguage())
