request for changing private status to protected

[Ronald]

Hi,
we are currently using vdrift for a simulation.
Until now we used an old (fixed) version, but we want to be up-to-date. For the simulation we have to build our own world including a track surface for the transmission. And here's the problem.
Due to the private status of the member "world", "track", "trackSurface" and so on in the collision_world.h, we are not able to do it properly without modifying your code.
If you could change the status of these members to "protected", it would be easier for us to use vdrift and keep up-to-date.

Thank you.
Ronald