message: backup service: save also optimized 2d grip map (like on close)
diff: @@ -2615,6 +2615,17 @@ bool CoreWrapper::triggerNewMapCallback(std_srvs::Empty::Request&, std_srvs::Emp
  bool CoreWrapper::backupDatabaseCallback(std_srvs::Empty::Request&, std_srvs::Empty::Response&)
  {
  NODELET_INFO("Backup: Saving memory...");
  + if(rtabmap_.getMemory())
  + {
  + // save the grid map
  + float xMin=0.0f, yMin=0.0f, gridCellSize = 0.05f;
  + cv::Mat pixels = mapsManager_.getGridMap(xMin, yMin, gridCellSize);
  + if(!pixels.empty())
  + {
  + printf("rtabmap: 2D occupancy grid map saved.\n");
  + rtabmap_.getMemory()->save2DMap(pixels, xMin, yMin, gridCellSize);
  + }
  + }
  rtabmap_.close();
  NODELET_INFO("Backup: Saving memory... done!");
  