function Direction(x, y)
{
    this.x = x;
    this.y = y;
}
@class Direction
A point value  in which the y component is 0 and the x component
is positive or negative for a right or left direction,
or the x component is 0 and the y component is positive or negative for
an up or down direction.

@param x     The horizontal component of the point.
@param y     The vertical component of the point.

@return A new \c Direction object.