Thickbox CSS, Styling, CSS performance, Exceptional rows, Menu container, Colro variatio

* Replaced thickbox CSS from WP framework with our own, preventing
required CSS overrides slowing down processing of runtime CSS
* System now automatically injects nxs-colorzen classes if a colorzen
value is used. Same for linkcolorvar's. This eases the css inheritance
implementation too.
* Improved CSS output (not perfect yet)
* Fixed Exceptional rows
* Menu containers have configurable border widths for main and sub items
* If none is set, the color variation picker shows nothing