code: function(color1, color2, factor) {
  		if (arguments.length < 3) { factor = 0.5; }
  		var hsl1 = this.rgb2hsl(color1);
  		var hsl2 = this.rgb2hsl(color2);
  		for (var i=0;i<3;i++) {
  			hsl1[i] += factor*(hsl2[i]-hsl1[i]);
  		}
  		return this.hsl2rgb(hsl1);
  	}
docs: Interpolate (blend) two colors with a given factor in HSL mode
  @param {number[]} color1
  @param {number[]} color2
  @param {float} [factor=0.5] 0..1
  @returns {number[]}