Theme generator and a VERY simple light theme

The light theme is not meant to be playable, what it is doing is giving a starting point for modifying creating themes. Most importantly getting all the relevant (for coloring) parts of the SC stylesheets and adding CSS variables to them for easier restyling.

I have recolored the simpler FC stuff, but huge parts of the game still use the simple color classes which makes recoloring not feasible.