Get an image downloader.

def getDownloader(self, url):
        """Get an image downloader."""
        filename = self.namer(url, self.stripUrl)
        if filename is None:
            filename = url.rsplit('/', 1)[1]
        dirname = getDirname(self.name)
        return ComicImage(self.name, url, self.stripUrl, dirname, filename, self.session, text=self.text)