iScroll4 滚动到底部检测

that.options里面添加事件名 (Line 139)onScrollLimit: null函数_move 结尾添加  (Line 490)if (newY<that.maxScrollY) that.options.onScrollLimit.call(that, e);函数 _startAni 结尾添加 (Line 768)if (step.y<that.maxScrollY) that.options.onScrollLimit.call(that);无论是滚动开始还是滚动结束，都会触发事件，而且是很多次。下面是初始化例子。myScroll = new iScroll('view', {onScrollLimit: function(){    console.log("I've past the end!");}});