OSPRay v1.4.2

• Several cleanups and bug fixes
  • Fixed memory leak where the Embree BVH was never released when an
    OSPModel was released
  • Fixed a crash when API logging was enabled in certain situations
  • Fixed a crash in MPI mode when creating lights without a renderer
  • Fixed an issue with camera lens samples not initilized when spp <= 0
  • Fixed an issue in ospExampleViewer when specifying multiple data files
• The C99 tutorial is now indicated as the default; the C++ wrappers do not
  change the semantics of the API (memory management) so the C99 version
  should be considered first when learning the API