* Add DETR

* drop return_pad_mask in PadBatch

* fix bs=2 of FCOS

* fix bs=2 of ttfnet

* fix cascade deploy

* speedup by paddle.expand

* reorganize the code, and fix bug

* fix typo

* remve comment

* reorganize code

* Revert "reorganize code"

This reverts commit 4f928c3a46b264ba8815978b914bf81a46b66b62.

* set weight

* set default config

* fix code style

* add solov2 enhance model

* support --eval for s2anet

* add spine dataset and config yml for s2anet

* add doc for s2anet

* update doc

* fix typo, test=document_fix

* add some comments, and update import

* support no label training

* fix load_crowd

* update to fit rbox

* add empty_ratio

* update configs

* support mask rcnn

* clean drop_empty for mot & keypoint

* refine is_crowd

* add fairmot

* rename pretrain_weights

* add comments; reuse focal loss and convnorm

* update comments

* 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

rename all Hrnet to HRNet

* 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

* 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 PP-YOLO tiny

* add pssdet model

* Add S2ANet model for Oriented Object Detection.

* update slim model

* fix skip quant

* add Distill model
* add distill+prune

* add fcos ttfnet coment, update modelzoo

* fix ttfnet coment