Add image for visualdl board.

* update doc in transfer learning

* update doc

* Add libra-rcnn, GCNet and iou loss intro doc.

* fix some docs link error

* rename config_doc

* Add doc for RCNN config.

* fix export_model doc link error

* sort out release/0.3 docs

* add new CHANGELOG

* add yolov4 in changelog

* add detailed doc
* add zh_CN doc of pssdet
* fix link

* Update docs
* Update README.md

* add map_fps fig

* optimize python path

* 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

* Remove `pycocotools` from `requirements.txt`

git version is required for numpy > 1.18

* Remove `cython`, add pip install doc

* add config link in model zoo

* fix link error

* add anchor free

* 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 iou aware module
* iouaware model zoo
* fix copyright

* add mobilenet v3 configs

* fix some comment

* fix memsize

* add yolov3_mobilenet_v3

* export config file in export_model.py

* add custom label_list & dump_box

* add infer_cfg.yml & doc

* export label_list to inference config

* update PaddleTensor to ZeroCopyTensor

* add multi-scale testing function in cascade rcnn clsaware architecture

* refine transfer learn

* refine transfer learning doc

fix oidv5 evaluation link

* Update README.md
* Update change logs
* Update docs/advanced_tutorials/inference/INFERENCE.md

* add padstride in cpp_infer and refine doc
* refine doc for export_model