Click-option-group

* Add `AllOptionGroup` class: all options from the group must be set or none must be set (PR [13](https://github.com/click-contrib/click-option-group/pull/13))
* Fix type hints
* Update docs

* Support multi-layer wrapped functions (PR [10](https://github.com/click-contrib/click-option-group/pull/10))
* Fix flake8 issues

* Add `hidden=True` to `_GroupTitleFakeOption` as a temporary workaroud for issue [4](https://github.com/click-contrib/click-option-group/issues/4)

* Add support for hidden options inside groups (PR [2](https://github.com/click-contrib/click-option-group/pull/2))

* Transfer the repo to click-contrib organisation

* Add true lineno in warning when declaring empty option group
* Update readme