• Added Catmull-Rom curve types.
• Added support for multi-level instancing.
• Added support for point queries.
• Fixed a bug preventing normal oriented curves being used unless timesteps were
  specified.
• Fixed bug in external BVH builder when configured for dynamic build.
• Added support for new config flag "user_threads=N" to device initialization
  which sets the number of threads used by TBB but created by the user.
• Fixed automatic vertex buffer padding when using rtcSetNewGeometry API function.