Method: Upload file and store it in temporary directory.
Method: Return url of all uploaded files.
Method: Order of HTML markup.
Method: Show the list of previously attached media.
Method: Return arguments for used by JS.
Method: Call save callback.
Method: Callback for replacing `apcode` shortcode.
Method: Callback called in @see ::pre_get.
Method: Image upload button.
Method: Prepare any data to be passed to the asynchronous postback