'Add a link to an external style file.
Also turns of the embedding of styles in the HTML'

def add_style_file(self, stylefilename, media=None):

    self.use_internal_css = False
    self.stylefilename = stylefilename
    if media:
        self.metatags.append(('<link    rel="stylesheet"    type="text/css"    href="%s"    media="%s"/>\n' % (stylefilename, media)))
    else:
        self.metatags.append(('<link    rel="stylesheet"    type="text/css"    href="%s"/>\n' % stylefilename))
