GitLab

* First draft

* Fix more things

* Improve more things

* Remove some head models

* Fix more things

* Add missing layers

* Remove tokenizer

* Fix more things

* Fix copied from statements

* Make all tests pass

* Remove print statements

* Remove files

* Fix README and docs

* Add integration test and fix organization

* Add tips

* Apply suggestions from code review
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Make tests faster, improve docs

* Fix doc tests

* Add model to toctree

* Add docs

* Add note about creating new checkpoint

* Remove is_decoder

* Make tests smaller, add docs
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>