Plone.app.mosaic

--------------------

- Update to mockup 5.0.0-alpha.12
- Packaging fixes
[petschki]

--------------------

- Refactoring of mosaic editor:

- ES6 class construction
- use mockup `pat-tinymce`
- use mockup `pat-plone-modal`
- get rid of $.mosaic initialization
- start getting rid of jQuery (uncompleted)

[petschki]

- Do not load mosaic editor on babel add form (`++addtranslation++...`).
[jensens]

- pyupgrade, black, isort
[jensens]

- Remove buildout and use mxdev/Makefile based approach.
Plone 6 only.
[jensens]

- Remove obsolete BS3 demo.
[jensens]

- Add row columns presets feature for the row stiles
[balavec]

- Fix advanced mode tile insert
[balavec]

- Update for Bootstrap 5
[agitator]

------------------

- Bugfix: Use TinyMCE `getContent()` to get editor contents on save
[frapell]

- Add ``bootstrapPath`` less variable.
Now the bundle can be built with ``plone-compile-resources``.
Contains an upgrade step.
[thet]

- Fix Flake8 errors
[jugmac00]

------------------------------

------------------

- Remove obsolete ``mockup-patterns-base`` -> use ``pat-base``
[petschki]

- fix TinyMCE drop-down menus in toolbar by implementing ``ui_container`` option
[petschki]

------------------

- Fix ``plone.app.contenttypes`` dependency for Plone 5.1
[agitator]

- Improve TinyMCE toolbar sticky computation
[frapell]

- fix .mosaic-width-quarter/.mosaic-width-three-quarters grid CSS to wrap correctly
[petschki]

- refactor mosaic-grid.less imports to avoid duplicated CSS selectors. (453)
[petschki]

- be more specific when removing top-margin
[petschki]

- safely read tile weight from registry
[petschki]

- refactor test-suites and add robot-tests
[petschki]

- Fix pip install command in ``.travis.yml``
[staeff]

- Fix byte-string join in ``main_template.py``
[1letter]

- Bug-fix in robot test
[1letter]