Blender Git Loki

Themes:
*Some more cleanup.
*Renamed active_theme to theme_area, active_theme will be useful, when we have multiple themes again.
*New layout (Theme Area selection is now expanded).

ToDo:
* Nice wrapping of all options for the different spaces, either manual or via auto generation.
Some items are missing, some are in different positions, altough they are available in different areas.