public unowned Object? new_palette_with_space (string name, Object space, Object format_u8, Object format_u8_with_alpha)
create a new palette based format, name is optional pass in NULL to get an anonymous format.
If you pass in with_alpha the format also gets an 8bit alpha channel. Returns the BablModel of the color model. If you pass in the same name the previous formats will be provided again.