这里是 loadingView的集合，会不定期增加一些效果。
另外每一种效果(也许)会对应一篇博客讲解如何实现。
博客讲解地址：http://androidwing.net/index.php/73
博客讲解地址：http://blog.csdn.net/wingichoy/article/details/50482271
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