* fix mot_source

* fix mot_source, test=document_fix

* add video infer for TestMOTReader

* format, test=documment_fix

* add fairmot

* rename pretrain_weights

* add comments; reuse focal loss and convnorm

* update comments

* 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