* add art model of deoldify

* update demo

* update psgan pretrained model link in the tutorial doc

* Refine some docs
* Update docs/en_US/data_prepare.md

* Update README
* Change docs dir to en_US and zh_CN
* Add paper reference
* Fix link

* refine codes docs

* add psgan and fom tutorial doc

* add video restore tutorial

* Add doc for Apps and refine some code
* Add how to switch cpu and gpu

* refine code

* test

* fix apps

* update readme

* rm unused code

* fix apps output when input is image

* clean code

* update requirements.txt