code: function(r, g,b) {
  		return this.setRGB([this.rgb[0] + r, this.rgb[1] + g, this.rgb[2] + b]);
  	}
docs: Adds the given RGB values as offsets to the current color. TColor will
  clip at black or white.
  @param r
  @param g
  @param b
  @return itself