code: function ObjectManager(game, ObjectConstructor, width, height) {
          this.game = game;
          this.ObjectConstructor = ObjectConstructor;
          this.objects = [];
          this.map = new RL.Array2d(width, height);
      }
docs: Manages a list of all objects and their tile positions.
  Handles adding, removing, moving objects within the game.
  @class ObjectManager
  @constructor
  @param {Game} game - Game instance this `ObjectManager` is attached to.
  @param {Object} ObjectConstructor - Object constructor used to create new objects with `this.add()`.
  @param {Number} [width] - Width of current map in tiles.
  @param {Number} [height] - Height of current map in tiles.