github 下载指定文件夹或文件

工具 svn

复制指定目录，比如：
https://github.com/googlevr/gvr-unity-sdk/tree/master/GoogleVR

将 tree/master 替换为 trunk

https://github.com/googlevr/gvr-unity-sdk/trunk/GoogleVR

命令

svn checkout https://github.com/googlevr/gvr-unity-sdk/trunk/GoogleVR