* 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

* fix deadlink in docs/tutorials/INSTALL_cn.md, slim/README.md and slim/extensions/distill_pruned_model/README.md

* update version require for ppyolo

* add COCO test-dev eval config and doc

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

add htc model 

* add py_func check in export_model

* refine error message

* Add `matrix_nms` op

* Make OP registration more robust

Add gridmask and random erasing methods

* update mbv3 ssdlite

* fix ssdlite link

add fleet training

* Add cutmix op(#88)

* fix voc dataset and docs

* add custom datsset demo