Bug fixes

Slick Browser 8.x-2.0-dev, 2020-02-23
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- Fixed for hidden edit button.
- Reverted the new Sortable library which disabled click events on buttons.
- Updated minimum core_version_requirement to 8.8.
- Renamed and refined few CSS classes to avoid potential conflicts.
- Replaced jquery.sortable with the new core sortable.

Slick Browser 8.x-2.0-dev, 2020-02-21
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- Increased modal iframe height from 520 to 640.

Corrected typos, added info on readme, etc.

Changes since 8.x-2.0-rc3:

• Issue #3114690 by sjerdo, mandclu, cajewell: Recurr\Exception\InvalidRRule
• Various CSS tweaks, especially to provide a more consistent experience in Claro and Adminimal

This release fixes an error introduced in the last release, and has styling tweaks to provide a more consistent experience across Seven, Claro, and Adminimal.

Drupal 9 compatability

Fixes Issue #3112854 ConfigImporterException: There were errors validating the config synchronization.