message: Rename random_sampler to random_generator
diff: #include <hcc/hc.hpp>
  -#include <visionaray/random_sampler.h>
  +#include <visionaray/random_generator.h>
  namespace visionaray
  {
  @@ -50,12 +50,12 @@ inline void hcc_sched_impl_frame(
  }
  // TODO: support any sampler
  - random_sampler<typename R::scalar_type> samp;// TODO
  + random_generator<typename R::scalar_type> gen;// TODO
  auto r = detail::make_primary_rays(
  R{},
  PxSamplerT{},
  - samp,
  + gen,
  x,
  y,
  rt_ref.width(),
  @@ -67,7 +67,7 @@ inline void hcc_sched_impl_frame(
  kernel,
  PxSamplerT(),
  r,
  - samp,
  + gen,
  frame_num,
  rt_ref,
  x,
  