https://github.com/seajs/seajs/issues/454
赞同ES6的做法：
主要模块打包后可根据实际需要动态加载需要的模块
http://blog.3gcnbeta.com/2014/05/27/%E4%B8%BA%E4%BB%80%E4%B9%88%E6%88%91%E6%8E%A8%E8%8D%90requirejs-%E8%80%8C%E4%B8%8D%E6%98%AFseajs/