Implement quit function in main menu

Will need to revise this in the future

main.c

@@ -99,6 +99,11 @@ int main(void)
         {
             sc_queue_clear(&key_buffer);
         }
+
+        if (curr_scene->state == SCENE_ENDED && engine.curr_scene == 0)
+        {
+            break;
+        }
     }
     free_sandbox_scene(&sandbox_scene);
     free_game_scene(&level_scene);

scenes/menu_scene.c

@@ -26,6 +26,9 @@ static void exec_component_function(Scene_t* scene, int sel)
         case 1:
             change_scene(scene->engine, 2);
         break;
+        case 3:
+            scene->state = SCENE_ENDED;
+        break;
         default:
         break;
     }