handle bitsy version as major and minor versions (uint); helper functions for game version/format

src/mock.rs

@@ -188,7 +188,8 @@ pub fn room() -> Room {
 pub fn game_default() -> Game {
     Game {
         name: "Write your game's title here".to_string(),
-        version: 6.5,
+        major_version: 6,
+        minor_version: 5,
         room_format: 1,
         palettes: vec![
             Palette {