public Circle(Pixel center, Pixel point) : this(center, center.distance(point)) { }
public ColorCircle(Pixel center, Pixel point, Color color) : this(center, center.distance(point), color) { }
public Circle(Pixel center, Pixel point) : this(center, center.distance(point)) { }
public ColorCircle(Pixel center, Pixel point, Color color) : this(center, center.distance(point), color) { }