message: Use struct for FactoryListBoxItem
diff: @@ -21,7 +21,7 @@ public:
  using SelectionChangedCallback = NAS2D::Signals::Signal<Factory*>;
  public:
  - class FactoryListBoxItem : public ListBoxItem
  + struct FactoryListBoxItem : public ListBoxItem
  {
  public:
  FactoryListBoxItem(Factory* newFactory) : factory(newFactory) {}
  