Physics integration and collision detection APIs

In order to support modern 3D user interfaces, a need to have collision detection and physics engine integration is a must.

We already have demo-grade implementations with Bullet3D physics engine, the learnings from this should be used to define collision detection APIs and produce easy-to-use guidance on physics engine (using Bullet 3D as reference).

Although we don't have direct customer requirements, this is relevant for us to engage in medical and industrial customers. Our competition sure has these and use them as argument against us.