* [Feature] add setr cityscapes benchmark

* change pretrain

* Update configs/_base_/datasets/cityscapes_768x768.py

Co-authored-by: Junjun2016 <hejunjun@sjtu.edu.cn>

* remove redundant keys

* remove redundant keys

* fix lint error

* update readme

* update pretrain

Co-authored-by: Junjun2016 <hejunjun@sjtu.edu.cn>

* add RandomRotate for transforms

* change rotation function to mmcv.imrotate

* refactor

* add unittest

* fixed test

* fixed docstring

* fixed test

* add more test

* fixed repr

* rename to prob

* fixed unittest

Co-authored-by: hkzhang95 <GodBlessZhk@outlook.com>