Replace rayEllipsoidIntersectionInterval with pointInEllipsoid.

The intersection line was being drawn quite differently from
the actual boundary of the intersection.  The latter was being
done correctly, the former was inaccurate.  I took the math from
the working one and applied it to the broken one.
Fix stray "shooting rays" effect spotted by @mramato.
Tighten the clamp.
Restore the check for missing the ellipsoid.
Merge pull request #697 from AnalyticalGraphicsInc/sensor-intersection

Fix sensor intersection rendering.