3d clothoid visualisation test

This 3d clothoid uses 2 primairy 2d clothoids to build a final 3d clothoid.
The first clothoid is build on xy plane.
The seond clothoid is build on the xz plane.
Then the first clothoid is interpolated from 0-1. Then for the second clothoid the nearest x value is fount, giving back the z value for the final clothoid.