Added a high score list

Hey, I just added a high score list. It really feels way harder to work on the game on my own (Instead of following a tutorial). I managed to do it but I did it with get_string rather than get_string_async. I heard it's bad practice becasue it pauses your entire game and adds a box. I will keep learning, it felt kinda intimidating to do it in the "correct" way. I will probably do changes to the map next, maybe some power ups or all of the above ha ha. Also the game keeps an internal score list of the 10 best scores, I thought that was kinda cool. It reminds me of old arcade machines where you fight with other people to get the best score.