tensorflow 模型保存(.meta .data .ckpt .pb)

由于TensorFlow 的版本一直在更新, 保存模型的方法也发生了改变
在python 环境,和在C++ 环境(移动端) 等不同的平台需要的模型文件也是不也一样的

参考下面的资料做一个详细的介绍:
https://stackoverflow.com/questions/44516609/tensorflow-what-is-the-relationship-between-ckpt-file-and-ckpt-meta-and-ckp

https://stackoverflow.com/questions/35508866/tensorflow-different-ways-to-export-and-run-graph-in-c/43639305#43639305

最准确的请参考Tensorflow官方文档:
https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/session_bundle/README.md

https://github.com/tensorflow/tensorflow/blob/master/tensorflow/python/saved_model/README.md