message: updates from code review feedback
  remove debug statements
diff: // num prims that _force_ a leaf; undef to revert to sah termination criterion
  //#define LEAF_THRESHOLD 2
  -#define DBG (0)
  -
  -#if DBG
  -static int leafCount = 0;
  -#endif
  -
  namespace ospray {
  template <typename T, int SIZE>
  @@ -42,11 +36,6 @@ namespace ospray {
  const size_t begin,
  const size_t end)
  {
  -#if DBG
  - std::cout << "building minmaxbvh " << begin << " " << end << std::endl;
  - PRINT(nodeID);
  -#endif
  -
  box4f bounds4 = empty;
  box4f centBounds4 = empty;
  @@ -68,10 +57,6 @@ namespace ospray {
  node[nodeID].lower = bounds4.lower;
  node[nodeID].upper = bounds4.upper;
  -#if DBG
  - std::cout << "bounds " << nodeID << " " << bounds4 << std::endl;
  -#endif
  -
  const box3f centBounds((vec3f &)centBounds4.lower,
  (vec3f &)centBounds4.upper);
  @@ -101,26 +86,12 @@ namespace ospray {
  primID[i] = tmp_primID[i];
  }
  -#if DBG
  - PRINT(l);
  - PRINT(r);
  - PRINT(begin);
  - PRINT(end);
  -#endif
  -
  float costIfSplit =
  1 +
  (1.f / safeArea(bounds4)) * (safeArea(lBounds) * (l - begin) +
  safeArea(rBounds) * (end - l));
  -#if DBG
  - PRINT(costIfSplit);
  - PRINT(costNoSplit);
  - PRINT(lBounds);
  - PRINT(rBounds);
  -#endif
  -
  if (
  #ifdef LEAF_THRESHOLD
  (end - begin) <= LEAF_THRESHOLD ||
  @@ -128,9 +99,6 @@ namespace ospray {
  ((costIfSplit >= costNoSplit) && ((end - begin) <= 7)) ||
  (l == begin) || (l == end)) {
  node[nodeID].childRef = (end - begin) + begin * sizeof(primID[0]);
  -#if DBG
  - leafCount++;
  -#endif
  } else {
  assert(l > begin);
  assert(l < end);
  @@ -178,10 +146,6 @@ namespace ospray {
  this->node.resize(this->node.size());
  root = node[0].childRef;
  -
  -#if DBG
  - PRINT(leafCount);
  -#endif
  }
  const void *MinMaxBVH2::nodePtr() const
  