Hsv properties for IBlock

Closes #35

Usage

level.Blocks.Add(new Block(216)
{
    PositionX = 30,
    PositionY = 30,
    Hsv = new Hsv()
    {
        Brightness = 0.5f,
        DeltaBrightness = true
    },
    AdditionalHsv = new Hsv()
    {
        Hue = 120,
        Saturation = 0.5f
    }
});

// Pay attention: block with id 1887 has only detail color, but hsv isn't additional
// AdditionalHsv used for detail color only when both color (base and detail) are present in the block
level.Blocks.Add(new Block(1887)
{
    PositionX = 60,
    PositionY = 30,
    Hsv = new Hsv()
    {
        Hue = 60
    }
});

Full Changelog: v0.2.24...v0.2.25