rename all Hrnet to HRNet

* Add BottomUp HigherHRNet for pose.
* reverse xtcocotools to pycocotools

* update ssd loss, make it faster test=develop

* update comments, test=develop

* ssd loss, fix bug when no object, text=develop

* update 2.0.1

* add script of dota_2_coco

* add args for dota_to_coco

* add script to generate test result of dota

* add loss weight for s2anet

* fix dy2st for s2anet

* fix code style

* remove rbox-iou-ops dependence

* fix name of ConvNormLayer for fcos solov2

* fix name in other head convbn

* fix yolo name, fix ttf_head name, test=document_fix

* add ttfnet enhance

* add doc

* fix pafnet training

* add ppyolov2

* fix bugs and modify docs

* modify code and doc according to review

* fix bugs while resolving conflicts

* add PP-YOLO tiny

* add pssdet model

* fix name of pretrain weights

* format, test=document_fix

* add senet

* add annotations according to review

* Add S2ANet model for Oriented Object Detection.

* update slim model

* fix skip quant

* fix warning

* refine ppdet file name

* unify bbox_utils

* add Distill model
* add distill+prune

* add fcos ttfnet coment, update modelzoo

* fix ttfnet coment

* support not pad gt in rcnn model

* add comment in reader

* 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>