titanscssc::adjustHsl PHP Method

    protected function adjustHsl($color, $idx, $amount)
    {
        $hsl = $this->toHSL($color[1], $color[2], $color[3]);
        $hsl[$idx] += $amount;
        $out = $this->toRGB($hsl[1], $hsl[2], $hsl[3]);
        if (isset($color[4])) {
            $out[4] = $color[4];
        }
        return $out;
    }