* 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>

* add quant clas

* fix load init model

* add quant

* add quant doc

* fix export model

* new usage of amp training.

* change the usage of amp and pure fp16 training.

* modified code as reviews

* Add RepVGG models

* Update model code

* Rename code

* format code

* add README of RepVGG

* fix save distillation model

* add note

* Add the DeiT models

* fix a training bug

* update the model init config

* update the License

* Add the ViT model

* fix vgg stop grad

* beautify code

* Update xception.py

* Update vgg.py

* Update regnet.py

* Update res2net.py

* Update res2net_vd.py

* Update resnest.py

* Update distillation_models.py

* fix reshape to flatten

* fix reshape

This reverts commit d5105825.

* add amp support for SE_ResNet50_vd

* updates for data_format

* Updata "*" to "paddle.multiply"

* Update "+" to "paddle.add"

* 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