message: added elaborative --help to ospBenchmark
diff: #include <windows.h>
  #endif
  +#include <iostream>
  +#include <string>
  +
  // Test init/shutdown cycle time //////////////////////////////////////////////
  static void ospInit_ospShutdown(benchmark::State &state)
  @@ -44,6 +47,47 @@ int main(int argc, char **argv)
  }
  #endif
  + // As there is no other way of customizing help output
  + // we have to detect `--help` by ourselves
  + for (int i = 1; i < argc; i++) {
  + if (std::string(argv[i]) == "--help") {
  + std::cout
  + << "The ospBenchmark is a performance measurement tool that "
  + "allows to assess the Intel OSPRay library performance on a target "
  + "hardware. It consists of many workloads that can be listed with "
  + "[--benchmark_list_tests=true] parameter and then selected for run "
  + "with [--benchmark_filter=<regex>] parameter. All test assets like "
  + "meshes or textures are generated procedurally during workload "
  + "initialization phase. If a test renders a frame it is stored "
  + "to an offscreen frame buffer."
  + << std::endl
  + << std::endl;
  +
  + std::cout
  + << "After tests completion a results table is printed. Each "
  + "table row corresponds to a single test or a single test "
  + "repetition. Number of repetitions can be controlled with "
  + "[--benchmark_repetitions=<num_repetitions>] parameter. Each "
  + "repetition completely recreates frame buffer, world, renderer "
  + "and camera. The table has the following columns:"
  + << std::endl;
  +
  + std::cout << " 'Benchmark' - the name of a test" << std::endl;
  + std::cout << " 'Time' - single iteration wall clock time" << std::endl;
  + std::cout
  + << " 'CPU' - single iteration CPU time spend by the main thread"
  + << std::endl;
  + std::cout
  + << " 'Iterations' - number of rendered frames, determined adaptively "
  + "to test for specified minimum time"
  + << std::endl;
  + std::cout << " 'UserCounters' - frames per second value" << std::endl
  + << std::endl;
  +
  + std::cout << "The list of all supported parameters:" << std::endl;
  + }
  + }
  +
  ospInit(&argc, (const char **)argv);
  auto DIR = utility::getEnvVar<std::string>("OSPRAY_BENCHMARK_IMG_DIR");
  