Color class

[nasser]

Colors should get a Color class that will support color arithmetic, interpolation, conversion and so on along with a use or apply method to set it as the current color.

# this
color 240, 128, 64

# would be the same as
my_red = Color.new 240, 128, 64
my_red.use

This would allow more advanced uses of colors that the present color method can't support. The color method would then act as the shorthand to the Color class.

[nasser]

Mostly fixed in 0b584c6, Color#use is not implemented yet, though.