* update doc, test=document_fix
Co-authored-by: NGuanghua Yu <742925032@qq.com>

* update det infer benchmark log

* s2anet fix export and deploy

* remove redundant code

* fix cpp for s2anet deploy

* fix bug of get_categories

* rename poly_to_rbox to poly2rbox

* add some comment for function

* add inference benchmark

* support not pad gt in rcnn model

* add comment in reader

* update solov2 some detail

* fix check paddle version

* add enable_static()

* follow comments

* remove blank line

* 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

* deploy code support camera

* add PPYOLO
Co-authored-by: Nlongxiang <longxiang@baidu.com>

* python deploy add log
* deploy add log & benchmark
* Update infer.py

* fix export_model doc link error

* sort out release/0.3 docs

* add new CHANGELOG

* add yolov4 in changelog

* fix with_background in export model

* fix coco_eval background