message: Store reference to icons in MineOperationsWindow
diff: @@ -41,8 +41,8 @@ private:
  private:
  MineFacility* mFacility = nullptr;
  - const NAS2D::Image mUiIcon;
  - const NAS2D::Image mIcons;
  + const NAS2D::Image& mUiIcon;
  + const NAS2D::Image& mIcons;
  NAS2D::ImageList mPanel;
  