OOSS

Try to fix non-successful physics loading.

Change load/save btRigidBody identification by m_worldArrayIndex. Still SceneNodes are stationary, maybe needs syncing.

Implement loading rigid bodies and linking with btRigidBody (dont work, because btCollisionObject::m_userIndex is not saved\!)

Add mandatory SceneNode naming and caching it for further physics load/save.

Enable passing arbitrary index to AutoIndexer::add (needed for loading saved simulation).