Translations:MediaWiki 1.21/wmf10/4/en

Most important changes

 * - Temporarily reverting change Ifbeae7e9 for 2 weeks to allow time to fix issues with TimedMediaHandler and other extensions.
 * - Deprecate in_string
 * - kill $wgUseDynamicDates
 * Extension - EventLogging
 * - Remove deprecated DevServer.php