The path created above is made up of arcs and line seg-
ments. An unpleasant feature of this is that since the curva-
ture is not continuous along the path, the robot has to make
a complete stop each time it meets a curvature discontinuity.
Since each roadmap node along the path corresponds to an
edge in the control roadmap, it is a simple matter to retrieve
all the control points along the path.