Bug: When I use addOnPageChangeListener instead setOnPageChangeListener, it will lead to some unpredictable problems.

[liyujiang-gzu]

When I use addOnPageChangeListener instead setOnPageChangeListener, it will lead to some unpredictable problems. Add the following code to fix it in LoopViewPager::
【当我使用addOnPageChangeListener代替setOnPageChangeListener，这将导致一些不可预知的问题。在LoopViewPager中添加以下代码作简单的修复：】

    @Deprecated
    @Override
    public void addOnPageChangeListener(OnPageChangeListener listener) {
        // only support one listener, use setOnPageChangeListener instead
        mOuterPageChangeListener = listener;
    }