Prepare colors to be exported.
       Flatten dicts and convert colors to util.Color()

def flatten_colors(colors):
    """Prepare colors to be exported.
       Flatten dicts and convert colors to util.Color()"""
    all_colors = {"wallpaper": colors["wallpaper"],
                  "alpha": colors["alpha"],
                  **colors["special"],
                  **colors["colors"]}
    return {k: util.Color(v) for k, v in all_colors.items()}