Convert a reST file to HTML.

def render_file(self, filename):
        """Convert a reST file to HTML.
        """
        dirname, basename = split(filename)
        with changedir(dirname):
            infile = abspath(basename)
            outfile = abspath('.%s.html' % basename)
            self.docutils.publish_file(infile, outfile, self.styles)
            return outfile