message: Use imageCache to load structure icons
  The imageCache owns the Image, so there is no need to new/delete the
  Image anymore.
diff: #include "FactoryListBox.h"
  +#include "../Cache.h"
  #include "../Constants.h"
  #include "../FontManager.h"
  @@ -56,14 +57,13 @@ FactoryListBox::FactoryListBox()
  */
  FactoryListBox::~FactoryListBox()
  {
  - delete STRUCTURE_ICONS;
  }
  void FactoryListBox::_init()
  {
  item_height(LIST_ITEM_HEIGHT);
  - STRUCTURE_ICONS = new Image("ui/structures.png");
  + STRUCTURE_ICONS = &imageCache.load("ui/structures.png");
  MAIN_FONT = &Utility<FontManager>::get().load(constants::FONT_PRIMARY, 12);
  MAIN_FONT_BOLD = &Utility<FontManager>::get().load(constants::FONT_PRIMARY_BOLD, 12);
  }
  