* fix problem due to empty bbox_pred and modify ppyolo docs, test=dygraph

* modify post process to avoid dy2st problem

* add quickstart doc, roadsign dataset

* add dygraph quant

* add ppyolo r18vd mbv3, yolov3 r50vd

* modify TestReader of ppyolo mbv3 r18vd

* add clip to avoid nan, modify ema to apply ema on bn mean and bn var

* fix code resulting in nan

* add yolov3 r50vd dcn configs

* finish yolo_series and fix some problems

* hide --bias flag and modify docs

* modify --bias and fix deploy/python/infer

* fix load_weight and no bbox output

* fit ttfnet

* fit for YOLOvd/PPYOLO/SSD

* eval in train

* add prune dygraph, test=dygraph

* fix slim readme and prune

* refactor rcnn, test=dygraph

* add mask_rcnn, test=dygraph

* add Faster RCNN & Faster FPN, test=dygraph

* update according to the review, test=dygraph

* fix modelzoo link

* fix config, remove some faster mask modelzoo

* fix readme

* fix reader exit error
* fix commet

* fix ssd mbv1 config

* fix trt infer

* ttfnet infer

* fix ttfnet deploy

* clean code

* add comment, fix config

* add comment, update modelzoo

* fix norm resize, update modelzoo

* add ppyolo in dygraph

* fix bugs

* modify configs

* polish docs, modify ema and add configs

* modify link of model

* fix bugs in ema

* modify code according to review

* modify minicoco configs

* fix dy fcos deploy

* fix dy fcos deploy, dtype float

* fix feed var need prune when export

* fix format

* fix format

* fix ssd ssdlite scheduler, add cosdecay

* fix mbv1v3 BatchNorm mean variance

* update ssd mbv1 voc modelzoo

* fix ssd mbv1 warmup, update modelzoo

* fix cosdecay

* add configs and modelzoo

* remove trainreader of batchsize 2

* add vd r34 x101

* fix typo

* add vd r34 x101

* add resnet dcn, clean code

* fix x101 width in py2

* add faster mask rcnn dcn configs and modelzoo

* fix dcn modelzoo

* clean dcn configs code

* add fcos dcn mstrain doc and config

* add dcn on resnet and head

* clean code

* add hrnet, test=develop

* add comment, test=dygraph

* move config file to hrnet, test=dygraph

* add 2x model

* add hrnet README

* update latest config structure, test=dygraph

* fcos infer

* fcos training

* fix stgraph fcosloss

* fcos doc

* fix dy_fcos

* add comment

* train eval deploy fcos

* remove fcos config, add comment

* fix iter_tic
Co-authored-by: Nnemonameless <nemonameless@qq.com>
Co-authored-by: Ngeorgenemo <nifeng@pku.edu.cn>

* add solov2 dygraph model, test=dygraph