def transform(point)
	    return point if point.is_a?(PointZero)
	    m = matrix
	    m ? Point[m * Point[point]] : point
	end
def transform(point)
	    return point if point.is_a?(PointZero)
	    m = matrix
	    m ? Point[m * Point[point]] : point
	end
Transform and return a new {Point}
 @param [Point] point	the {Point} to rotate into the parent coordinate frame
 @return [Point]   the rotated {Point}