message: fix reset accumulation
diff: @@ -401,8 +401,10 @@ float MultiDevice::getVariance(OSPFrameBuffer _fb)
  void MultiDevice::resetAccumulation(OSPFrameBuffer _fb)
  {
  MultiDeviceObject *o = (MultiDeviceObject *)_fb;
  - LocalFrameBuffer *fb = (LocalFrameBuffer *)o->objects[0];
  - fb->clear();
  + for (size_t i = 0; i < subdevices.size(); ++i) {
  + LocalFrameBuffer *fbi = (LocalFrameBuffer *)o->objects[i];
  + fbi->clear();
  + }
  }
  // Frame Rendering //////////////////////////////////////////////////////
  