* Function: tag
* Return html code for a tag
*/
-# NB 06.12.16 public static function h1($content='',$attrs='') { return self::tag('h1',$content,$attrs); }
-# NB 06.12.16 public static function div($content='',$attrs='') { return self::tag('div',$content,$attrs); }
-# NB 06.12.16 public static function pp($content='',$attrs='') { return self::tag('p',$content,$attrs); }
public static function tag($tag,$content='',$attrs='') {
static $is_html = null;
if ($is_html === null) $is_html = preg_match('/ml$/',self::content_type()) ? true : false;