* 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 model_zoo package for configs directory structure change

* update README

* update prepare dataset and deploy document, test=dygraph

* simplify CMakeList, test=dygraph

* add cpp doc link, test=dygraph

* remove WITH_STATIC_LIB, test=dygraph

* update doc, test=dygraph

* fix cmakelist, test=dygraph

* split EXPORT_MODEL.md, update READEME.md, add QA on deploy README.md, test=dygraph

* Using same env as paddle_inference_lib when deploy, test=dygraph

* fix typo, test=dygraph

* 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