[ODE] zero size in dNormalize4()

[Remi Ricard]

Hi,

> What causes the ODE Message 2: vector has zero size in dNormalize4() error?
>   

This can also be caused by 2 bodies that have a common edge or face 
colliding with a third body.
If the collision point is on the edge it can cause this kind of error.

Ex)
   Body A              ||  Body B
-------------------||--------------------------
                            ^
                          /    \
                       /         \
                      /           \
                       Third body


Remi