remove redundant comment

src/game.rs

@@ -320,9 +320,6 @@ impl Game {
     pub fn merge(&mut self, game: Game) {
         // ignore title, version, room format, room type, font, text direction
 
-        // maybe we need hashmaps of old->new IDs, for each type of ID?
-        // we need functions for "add sprite" etc. that return the newly generated valid ID
-
         let mut palette_id_changes:  HashMap<String, String> = HashMap::new();
         let mut tile_id_changes:     HashMap<String, String> = HashMap::new();
         let mut dialogue_id_changes: HashMap<String, String> = HashMap::new();