* fix sklearn params

* fix sklearn params

* fix metric order

* add multi xpu support for PaddleClas about dygraph

* add dygraph multi xpu support

* fix repvgg eval

* fix dp training

* fix single card train

* fix loss reduce from dict to list

* remove note

* add find_unused_parameters param

* fix default val

* support bs>1

* Support Visual DL

* Fix VDL

* Add doc of VDL, test=document_fix

* Add the en doc of VDL, test=document_fix
Co-authored-by: Nlittletomatodonkey <2120160898@bit.edu.cn>

* new usage of amp training.

* change the usage of amp and pure fp16 training.

* modified code as reviews

* add eta info

* rm duplicate desc

* Adapt to PaddleHub2.0 to eliminate warning
* Fix the training log format

* fix predict

* fix export model

* fix doc

* Fix the timing of hubserving

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

* Update the download link of Paddle Inference Library

* 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