Mkdocs-gallery

- Examples expected to fail are now correctly skipped in case of identical md5 hash, too. Fixes [34](https://github.com/smarie/mkdocs-gallery/isues/34). PR [#39](https://github.com/smarie/mkdocs-gallery/pull/39) by [mchaaler](https://github.com/mchaaler).

See [documentation page](https://smarie.github.io/mkdocs-gallery/changelog) for details.

- `matplotlib` was still not optional by default because of the associated `image_scraper` that was called even when not used. It is now truly optional. Fixed [24](https://github.com/smarie/mkdocs-gallery/issues/24)

See [documentation page](https://smarie.github.io/mkdocs-gallery/changelog) for details.

- Fixed `KeyError` issue when using a minimalistic configuration. Fixed [22](https://github.com/smarie/mkdocs-gallery/issues/22).
- `matplotlib` is now optional. Fixed [24](https://github.com/smarie/mkdocs-gallery/issues/24)

See [documentation page](https://smarie.github.io/mkdocs-gallery/changelog) for details.

- Fixed packaging issue: static resources were not included in wheel. Adopted `src/` layout. Fixed [19](https://github.com/smarie/mkdocs-gallery/issues/19).

See [documentation page](https://smarie.github.io/mkdocs-gallery/changelog) for details.

- Code output now have a correct height limit. Fixed [7](https://github.com/smarie/mkdocs-gallery/issues/7)
- Fixed the "Notebook Style Example" tutorial. Fixed [17](https://github.com/smarie/mkdocs-gallery/issues/17)

See [documentation page](https://smarie.github.io/mkdocs-gallery/changelog) for details.

- Completed the gallery of examples. Fixed [1](https://github.com/smarie/mkdocs-gallery/issues/1)
- Fixed HTML repr (example 2, typically used to display pandas tables). Fixed [11](https://github.com/smarie/mkdocs-gallery/issues/11)
- Binder badges now work correctly. Fixes [5](https://github.com/smarie/mkdocs-gallery/issues/5)
- "Edit page" links (pencil icon at the top) now work as expected: they take the user to the source python file used to generate the page. It also works for gallery readme pages ! Fixes [8](https://github.com/smarie/mkdocs-gallery/issues/8)
- backreferences files are now written but it is still not clear how they should be used in a mkdocs context, see [10](https://github.com/smarie/mkdocs-gallery/issues/10)
- Fixed most flake8 issues and warnings.

See [documentation page](https://smarie.github.io/mkdocs-gallery/changelog) for details.