redo version as a struct

src/lib.rs

@@ -23,7 +23,7 @@ use dialogue::Dialogue;
 use ending::Ending;
 use exit::{Transition, Exit};
 use text::{Font, TextDirection};
-use game::Game;
+use game::{Game, Version};
 use palette::Palette;
 use image::Image;
 use item::Item;