Linear BVH implementation

[Q-Minh]

Hi @zfergus ,

I just finished my BVH implementation of Maximizing Parallelism in the Construction of BVHs,
Octrees, and k-d Trees. In case you were interested, it can be found here, together with its associated kernels. These were explicitly written with discrete collision detection in mind, but hopefully, it is not too hard to account for linear trajectories in bounding box computations. Thanks for the insightful discussions and I share these in case it might be of some use in building the collision detection dataset you were working on!