[ODE] ODE for volume checking

[Erwin de Vries]

Hi,

Currently ODE allows 0 to be specified in the flags section of dCollide().
Currently it ignores that, and forces it into 1. Couldnt we use this '0
contact mode' as a simple 'in or out' query? Returning 1 should be
interpreted as "Yes there is a collision, but i didnt generate the contacts.
=P". So, no joints can be created, but this information can be used for lots
of other things.

Currently this is already possible by simply ignoring the generated contact,
but there is some wasted work done by the collision functions here. I had a
quick look trough the sources of the colliders, and i'd say its quite easy
to modify them to do this.

Russ, do you have any intent on doing this anytime soon?

Erwin