* add VisualDL and save best_model

* add VisualDLWriter callback

Merge dygraph branch into master branch.
Co-authored-by: NFDInSky <48318485+FDInSky@users.noreply.github.com>
Co-authored-by: Nsunxl1988 <47514455+sunxl1988@users.noreply.github.com>
Co-authored-by: Nwangguanzhong <jerrywgz@126.com>
Co-authored-by: Nwangxinxin08 <69842442+wangxinxin08@users.noreply.github.com>
Co-authored-by: Nwanghuancoder <wanghuancoder@163.com>
Co-authored-by: Ncnn <liuhui29@baidu.com>
Co-authored-by: NGuanghua Yu <742925032@qq.com>
Co-authored-by: NKaipeng Deng <dengkaipeng@baidu.com>
Co-authored-by: Nroot <root@bjyz-sys-gpu-kongming0.bjyz.baidu.com>

Add image for visualdl board.

* Remove `pycocotools` from `requirements.txt`

git version is required for numpy > 1.18

* Remove `cython`, add pip install doc

* [cherry-pick] Fix v0.2 docs (#258)

* fix save checkpoint in quantization (#257)

* fix save checkpoint in quantization
* fix details

* Fix softlink (#256)
Co-authored-by: NLiufang Sang <slf12thuss@163.com>

* [cherry-pick] add prune benchmark (#262)

* add prune model latency (#260) & fix run command for windows (#261)

* Cherry-pick update reader config (#269)

* Force `cudnn` backend for depthwise convs when fp16 is enabled (#271)

* fix weights path (#274)

* cherry-pick refine fruit config (#289)

* cherry-pick polish doc (#287)

* cherry-pick fix oidv5 link (#296)

cherry-pick fix oidv5 link

* [cherry-pick] polish slim model zoo (#313)

* polish slim README

* refine pedestrian_yolov3_darknet.yml and vehicle_yolov3_darknet.yml in contrib (#324)

* fix yolo configs (#332)

* cherry pick polish doc (#329)

* refine config (#336)

* [cherry pick] refine sensitive link (#334)

* refine sensitive link

* add YOLOv3Loss.batch_size comments (#348)

* add deploy with python

* update README

* support TRT and Executor

* update cpp_infer for paddle latest

* support fixed shape of model

* polish code

* supoort trt

* support TRT&Executor

* deploy/python : fix coding style problems

* update requirements.txt

* update deploy/python docs
Co-authored-by: NGuanghua Yu <742925032@qq.com>
Co-authored-by: NLiufang Sang <slf12thuss@163.com>
Co-authored-by: NKaipeng Deng <dengkaipeng@baidu.com>
Co-authored-by: Nwangguanzhong <jerrywgz@126.com>
Co-authored-by: NYang Zhang <yangzhang@live.com>
Co-authored-by: littletomatodonkey <dazhiningsibuqu@163.com>
Co-authored-by: NFlyingQianMM <245467267@qq.com>
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* add mask operations in RandomExpand and RandomCrop

* remove all [] in cropped polys

* is_poly -> _is_poly()

* change the judgment on whether there are polygons

* abstract is_poly to op_helper.py

* add is_mask_expand and is_mask_crop in RandomExpand and RamdomCrop

* refine code & doc for cpp_infer

* add cython for pycocotools install

* Polish Reader to simplify preprocessing logic.
#  sample_transforms-> make batch -> batch_transforms in Reader.
* Clean some code
* Imporve yolov3_r50vd_dcn_obj365_pretrained_coco 41.4 to 41.8.
* Update all configs.

In PaddleDetection,  making use of tb-paddle to record data, so as to display in TensorBoard.  (#3295)

* use tb_paddle to log data
including:

* loss
* mAP
* image

* modified:   requirements.txt
* modify the missing argument --use_tb
* modify GETTING_STARTED.md and docs/GETTING_STARTED_cn.md

add the argument of tb-paddle in docs.
* optimize the display name of image displaying.

* Rename object_detection to PaddleDetection
* Small fix for doc