Embree v2.10.0

• Added a new curve geometry which renders the sweep surface of a
  circle along a Bézier curve.
• Intersection filters can update the 'tfar' ray distance.
• Geometry types can get disabled at compile time.
• Modified and extended the ray stream API.
• Added new callback mechanism for the ray stream API.
• Improved ray stream performance (up to 5-10%).
• Up to 20% faster morton builder on machines with large core counts.
• Lots of optimizations for the second generation Intel® Xeon Phi™ coprocessor codenamed Knights Landing.
• Added experimental support for compressed BVH nodes (reduces node
  size to 56--62% of uncompressed size). Compression introduces a
  typical performance overhead of ~10%.
• Bugfix in backface culling mode. We do now properly cull the
  backfaces and not the frontfaces.
• Feature freeze for the first generation Intel® Xeon Phi™ coprocessor
  codenamed Knights Corner. We will still maintain and add bug fixes
  to Embree v2.9.0, but Embree 2.10 and future versions will no longer support it.