* Update xception.py

* Update vgg.py

* Update regnet.py

* Update res2net.py

* Update res2net_vd.py

* Update resnest.py

* Update distillation_models.py

* Fix "tar" to "pdparams" to adapt to dygraph

* Update the download link of Paddle Inference Library

* for supporting paddle rc1

* add resnet_amp.py file for resent50 amp training.

* change yaml file name

* fix time sta for cpp

* fix time sta for cpp

* Fix serial number error

* Fix the environment description of running PaddleClas

* Add the overview of other models

* Modify the pretrained models to dygraph

* support fp16 training

* Use compiled training program

* Change timing ips.

* Use dali

* add pure fp16 training

* fix a bug, which will not use fuse pass using pure fp16 training.

* modify code as review

* modify loss, so that it will use different loss when using pure fp16 training.

* remove some fluid API

* add static optimizer.

* fix eval script

* fix dali shell

* Add FAQ 20201207

* Fix FAQ20201207

add se hrnet64_c

* fix pred

* fix resnest

* fix hrnet se

* fix se for export

* add shells, test=develop