Cmsplugin-blocks

* Upgraded to ``django-smart-media>=0.3.0`` to fix plugin form layout on file inputs,
close 20;
* Cleaned Sass sources from old useless fileinput sources;
* Updated PO and MO files, added missing blank locale for 'en';
* Fixed plugin form to use the proper ``features`` field label;
* Removed all signal receiver ``auto_purge_files_on_change`` usage from all plugins to
remove a misbehavior with file purge and page publication. This means files related
to deleted plugin won't be automatically removed anymore, close 22;

Major release to upgrade to modern backend supports and some other improvements.
Your project need to upgrade to the new requirements supports to be able to migrate to
this version and further.

* Removed support for Python less than 3.8;
* Removed support for Django less than 3.2;
* Removed support for DjangoCMS less than 3.11.x;
* Added support for Python from 3.8 to 3.10;
* Added support for Django from 3.2 to 4.1;
* Added support for DjangoCMS from 3.11.x;
* Added new field ``features`` on every block, this field won't be showed on default
installation since there is no defined features. User have to define them in
respective plugin settings;
* Added new plugin ``container``;
* Updated default plugin templates, it just inherits from the test one. User will have
to copy the respective plugin test template to create their own and define them in
settings;
* Upgrade package setup, Makefile, documentation configuration, Tox configuration;
* Removed included ``SmartMedia`` stuff in profit of ``django-smart-media``
requirement;
* Rewrited tests;
* Renamed default settings module from ``settings`` to ``defaults``;
* Documentation has been updated for the new plugin ``Container`` and for installation
document. A next version should comes further to restructurate documentation for
improvements;
* Added modern sandbox frontend with ``bootstrap=^5.1.3`` built with Node.js;

Release fix for package and documentation publishing on ReadTheDoc.

Manifest file was not accurate and package has been wrongly built
and so was missing the templatetags modules.

The resulting package was incorrect and ReadTheDoc could not build the
documentation.

**This version package is broken, you should install v0.7.1 instead which fix this version issues**


Better plugin forms ergonomy and documentation.

* Added new setting `BLOCKS_ENABLED_PLUGINS` which list plugins to enable
for usage. Disabled plugins won't be visible but their models are still
created in your database. **WARNING:** You need to update your project
settings to add this new setting if you don't include the app settings;
* Added missing field `title` for Slide item form;
* Added `FileInputButton` widgets to use instead FileInput;
* Added `ClearableFileInputButton` widgets to use instead ClearableFileInput;
* Added custom stylesheets for every plugin admin forms to improve their ergonomy;
* Added Boussole to development requirement to build CSS from Sass sources;
* Mute the `RemovedInDjango40Warning` warning until DjangoCMS has fixed its
usage of `ugettext_lazy`;
* Added missing default settings `SMART_FORMAT_AVAILABLE_FORMATS`;
* Added documentation in `docs` with Sphinx and livereload;

This is a major refactoring which may involve breaking changes for some custom
usages.

* Added full test coverage;
* Added tox configuration;
* Modified every plugin templates to be cleaner and flawless;
* Added `title` attribute to SlideItem model;
* Use `FileField` instead of `ImageField` for image fields in every plugin
so we can use SVG;
* Add a new template tag `media_thumb` with smart format guessing instead of
Sorl tag `thumbnail` on images in every plugin templates;