* fix some docs error

* fix name of pretrain weights

* format, test=document_fix

* Add S2ANet model for Oriented Object Detection.

* refine ppdet file name

* unify bbox_utils

* add Distill model
* add distill+prune

* support mask_rcnn for kunlun

* minor

* update solov2 some detail

* fix check paddle version

* check md5 before load weights.

* support infer for SOLOv2

* 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

* check md5 after weights download

* fix voc mAP %.

* add roadsign_voc dataset and update FAQ

* Add roadsign_voc dataset, updatea FAQ.md, and add yolov3_voc and yolov3_coco config template files.

* remove configs/templates

* convert config template file to md file, update comment

* mv config annotation file to config_annotation.

* move to docs/advanced_tutorials/config_doc

* rename

* update style

* update 2019-->2020

* update yolov3_mobilenet_v1_roadsign.md

* addd preprocess as yolov3_reader

* remove yolov3_mobilenet_v1_roadsign.md and add yolov3_mobilenet_v1.md

* fix typo

* add py_func check in export_model

* refine error message

* fix voc dataset and docs

* add custom datsset demo

* add version check

* update version check & python version for cornerpool

* fix with_background in export model

* fix coco_eval background

* add yolov4

* Make logger less noisy

* Fix indent

* update check config

* fix slim/xx

* code for cornernet

* add doc

* refine custom op

* refine code from review comments

* refine doc

* update doc

* update code

* add cornernet_squeeze_mixup_cosine config

* update code

* update code