HACD bad geometry

[AndresTraks]

In the C# convex decomposition demo, HACD creates 40 clusters, in libbulletc, it creates 10 clusters, in BulletSharp and the original bullet demo, 8 clusters are created.

All of the input data and settings seem to be exactly the same, but the output is different. Might be a floating-point precision issue.

[ShadowTeolog]

#88 maybe this happen