- switched the frustum/box intersection code to double. With large
scenes, we were getting very wrong intersection points (up to 1m off).
This doesn't seem to happen with doubles.
- reject points that end-up outside the frustum
- made LiSPSM code more robust against the problem above. When points
were falsely placed behind the near plane (due to bad intersections),
we could end-up with NaN (sqrt of negative numbers).
beb2f74bdc