* fix RCNN dygraph to static

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 solov2 model

* fix train batch size

* add solov2_r101_vd_fpn_3x

* fix batch size and update modelzoo

* refactor code of solov2

* fix deploy/python

* fix deploy

* [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>
Co-authored-by: NChanningss <chen_lingchi@163.com>