* optimize python path

* add yolov4

* Organize and document mobile models

* Clean up trailing whitespaces

* Change bullet type

* Minor wording fixes

* Fix yolo naming

* Add link in repo README.md

* add serving export model
* add paddle serving client in requirement.txt
* remove redundant code with codestyle check
* fix export model doc
* fix according to professional reviews
* move paddle serving model export tutorial to the last of doc

* Make logger less noisy

* Fix indent

* update check config

* fix slim/xx

use_fine_grained_loss: true

* Remove `pycocotools` from `requirements.txt`

git version is required for numpy > 1.18

* Remove `cython`, add pip install doc

* fix deploy

* Revert back to `fluid.clip` for gradient clipping

current API is in flux, wait for it to stabilize

* Please CI

still buggy

* add config link in model zoo

* fix link error

* add anchor free

* #add dcn on  FCOS_head and backbone

* code for cornernet

* add doc

* refine custom op

* refine code from review comments

* refine doc

* update doc

* update code

* add cornernet_squeeze_mixup_cosine config

* update code

* update code

* deploy/cpp : Update cpp ineference solution

* add README.md to deploy

* deploy/cpp : add PadStride

* deploy/cpp : add output visualization

* deploy/cpp: add video support

* fix coding style problem

* deploy/cpp : add README.md

* deploy/cpp : update docs

* deploy/cpp : update linux build scripts

* deploy/cpp : update linux build docs

* udpate docs

* deploy/cpp : update windows build docs

* depoy/cpp: fix coding style

* fix coding style

* Create CMakeSettings.json

* Update README.md

* Update windows_vs2019_build.md

* Update CMakeLists.txt

* Update linux_build.md

* Update CMakeLists.txt

* deploy/cpp : update linux build script

* update doc structures and support arch Face

* add moile-side rcnn server model

* support face detection in python inference

* support face detection in python deploy