* add fairmot

* rename pretrain_weights

* add comments; reuse focal loss and convnorm

* update comments

* fix hsv randomaffine

* fix nms return_index

* fix gt_ide by tid_start_index

* add deepsort configs comments

* fix doc, add readme_cn

* fix doc

* fix jde doc and metric test_mode

* add image_lists

* add readme_cn

* fix eval snapshot_epoch

* add config for jde and deepsort, add engine metric tools

* add mot_metrics

* fix configs engine and others

* fix configs others

* move configs

* fix ap_per_class, fix doc

* fix test_mode, seqs

* fix test_mode to metric

* fix JDE arch metric

* clean requirement

* add to requirement

* 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 mot data

* fix operators, source

* fix data source transform

* fix parse_dataset register_op

* fix scale_factor, RandomAffine

* add assert for check

* fix ci

remove doubled words

* fix voc eval

* remove debug code

* add comments

* update comment for collate_batch

* refine yolov3 configs

* fix dataset problem

* add ext_op build doc, test=fix_document

* add note for JetPack version with machine

* update doc on develop, test=document_fix

* update dependency of ppdet and paddle, test=document_fix

* update docs, test=document_fix

* fix some docs error

* add ttfnet enhance

* add doc

* fix pafnet training

* move ssld model, test=document_fix

* fix typo, test=document_fix

* add ppyolov2

* fix bugs and modify docs

* modify code and doc according to review

* fix bugs while resolving conflicts

* update README

* update doc, test=document_fix

* add citation

* update citation and ppyolo doc

* add PP-YOLO tiny