/**
                         * @description
                         *
                         * CG.Menu collects buttons an displays them with the defined margin
                         *
                         ```
                        
                         var menu = new CG.Menu({
                           x: 100,
                           y: 100,
                           margin: 10
                         })
                        
                         button = new CG.Button({
                            image: Game.asset.getImageByName('button'),
                            position: new CG.Point(Game.width2, 100),
                            text: 'Menu Button 1',
                            font: font,
                            callback: callbackTest
                         })
                         button.name = '#mbutton 1#'
                         menu.addButton(button)
                        
                         button = new CG.Button({
                            image: Game.asset.getImageByName('button'),
                            position: new CG.Point(Game.width2, 100),
                            text: 'Menu Button 2',
                            font: font,
                            callback: callbackTest
                         })
                         button.name = '#mbutton 2#'
                         menu.addButton(button)
                        
                         button = new CG.Button({
                            image: Game.asset.getImageByName('button'),
                            position: new CG.Point(Game.width2, 100),
                            text: 'Menu Button 3',
                            font: font,
                            callback: callbackTest
                         })
                         button.name = '#mbutton 3#'
                         menu.addButton(button)
                        
                         // add the menu to the layer
                         layermenu.addElement(menu)
                        
                         ```
                         *
                         * @class CG.Menu
                         * @extends CG.Class
                         *
                         */
                        CG.Class.extend('Menu', {
                            /**
                             * Options:
                             * x {number}
                             * y {number}
                             * margin {number}*
                             *
                             * @method init
                             * @constructor
                             * @param options {object}
                             * @return {*}
                             */
                            init: function (options) {
                                CG._extend(this, {
                                    /**
                                     * @property x
                                     * @type {Number}
                                     */
                                    x: 0,
                                    /**
                                     * @property y
                                     * @type {Number}
                                     */
                                    y: 0,
                                    /**
                                     * @property margin
                                     * @type {Number}
                                     */
                                    margin: 0,
                                    /**
                                     * @property step
                                     * @type {*}
                                     */
                                    step: 0,
                                    /**
                                     * @property buttons
                                     * @type {Array}
                                     */
                                    buttons: []
                                })
                        
                                if (options) {
                                    CG._extend(this, options)
                                    this.step = this.y
                                }
                                return this
                            },
                            /**
                             * @description adds an CG.Button to the buttons array
                             *
                             * @method addButton
                             *
                             * @param {button} button
                             */
                            addButton: function (button) {
                                this.buttons.push(button)
                            },
                            /**
                             * @method update
                             */
                            update: function () {
                                this.buttons.forEach(function (button) {
                                    button.update()
                                })
                            },
                            /**
                             * @method draw
                             */
                            draw: function () {
                                this.buttons.forEach(function (button) {
                                    button.position.x = this.x
                                    button.position.y = this.step
                                    button.draw()
                                    this.step += button.height
                                    this.step += this.margin
                                }, this)
                                this.step = this.y
                            }
                        })