&$parser: Parser object
&$ig: ImageGallery object
+'BeforeWelcomeCreation': before the welcomecreation message is displayed to a newly created user
+&$welcome_creation_msg: MediaWiki message name to display on the welcome screen to a newly created user account
+&$injected_html: Any HTML to inject after the "logged in" message of a newly created user account
+
'BitmapHandlerTransform': before a file is transformed, gives extension the
possibility to transform it themselves
$handler: BitmapHandler