add and refactor game menus

- add pause menu closes #55
- add gamepad support for game over screen #63
- add ship destruction closes #27

Author: it-me-joda

src/audio/mod.rs

@@ -89,6 +89,9 @@ fn on_play_soundtrack_event(
     };
 
     for audio_player_entity in audio_player.iter_mut() {
+        if audio_player_entity.1.0 == track_handle {
+            return;
+        }
         commands.entity(audio_player_entity.0).despawn();
     }