message: fix accumulation bug with dynamic load balancing
diff: @@ -1048,12 +1048,11 @@ namespace ospray {
  return 0;
  const auto tileNr = tile.y * numTiles.x + tile.x;
  - // Will: Why was the accumID incremented here and not at end frame?
  - // Could it be for some tile which we render multiple times a frame
  - // on a node? Maybe Johannes is using this for the error refinement
  - // or something?
  + // Note: we increment here and not in endframe because we
  + // can render the same tile multiple times with different accumulation
  + // IDs when using dynamic load balancing.
  tileInstances[tileNr]++;
  - return tileAccumID[tileNr];
  + return tileAccumID[tileNr]++;
  }
  float DFB::tileError(const vec2i &tile)
  @@ -1083,9 +1082,6 @@ namespace ospray {
  memset(tileInstances, 0, sizeof(int32)*getTotalTiles()); // XXX needed?
  - for (int i = 0; i < getTotalTiles(); ++i)
  - ++tileAccumID[i];
  -
  if (mpicommon::IamTheMaster()) // only refine on master
  return tileErrorRegion.refine(errorThreshold);
  else // slaves will get updated error with next sync() anyway
  