+ Added self-references to Wess variables. In other words: up until now, whenever you redefined a variable, you couldn't re-use its existing value inside the definition. Now you can. In yet other words: `$big_font = "Segoe UI", $big_font` is now possible in a sub-skin if you want to add a new default font but want to keep the existing font stack as a fallback. Okay, are we good now? ;) (Class-CSS.php)