float16 related work by Kexin
Created by: wangkuiyi
- float16 type definition and design doc: https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/platform/float16.h https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/data_type/float16.md
- Make some operators work with float16: https://github.com/PaddlePaddle/Paddle/issues?utf8=%E2%9C%93&q=is%3Aissue+float16+support+
- Make the inference transpiler support float16: https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/inference_transpiler.py
- Correctness verification reused https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/tests/book/test_image_classification.py
- Performance benchmarking: https://github.com/kexinzhao/Paddle/blob/float16_demo/python/paddle/fluid/tests/demo/float16/run_float16_demo.sh
- Benchmarking report: https://github.com/kexinzhao/Paddle_benchmark/blob/master/float16_benchmark.md