* Add RegNet, docs/refactor TBD

* Support RegNet

* Add RegNets

* Modify docs and refactor code

* fix pre-train bug

* Performance ready

* Use public model weights

* Performance & settings done

* Fix unittest bug

* Try another way of test config

* Add unittest and refactor

* Reformat

* Finish refactor regnet

* merge tests

* fix conflicts

* Fix resnext CI bug

* rename parameter

* Add ref link & clean _delete_

* tweaks of doc

* try resnext doctest

* add expansion in block

* remove doctest of resnext