Open VKL v1.0.0

• The version 1.0 release marks long term API stability (until v2.0)
• Open VKL can now be built for ARM CPUs that support Neon
• Iterator API updates:
  • Introducing interval and hit iterator contexts, which hold iterator-specific configuration (eliminates value selector objects)
  • Interval and hit iteration is now supported on any volume attribute
  • Interval iterators now include a time parameter
  • Interval iterators now support the intervalResolutionHint parameter, replacing maxIteratorDepth and elementaryCellIteration
• Supporting configurable background values; default is now VKL_BACKGROUND_UNDEFINED (NaN) for all volume types
• vklGetValueRange() now supports all volume attributes
• Added ISPC-side API bindings for vklGetNumAttributes() and vklGetValueRange()
• Structured regular volumes:
  • Added support for tricubic filtering
  • More accurate gradient computations respecting filter mode
  • Hit iteration robustness improvements
• VDB volumes:
  • Interval and hit iteration robustness improvements
  • Corrected interval iterator nominalDeltaT computation for non-normalized ray directions and non-uniform object-space grid spacings
  • Fixed bug which could cause incorrect value range computations for temporally varying volumes
• vklExamples additions demonstrating:
  • Multi-attribute interval / hit iteration
  • Configurable background values
  • Temporally varying volumes
• Superbuild updates to latest versions of dependencies
• Now requiring minimum versions:
  • Embree 3.13.1
  • rkcommon 1.7.0
  • ISPC 1.16.0