Replace jquery.mwCoolCats with mediawiki.widgets.CategorySelector
It offers a much prettier and much more usable user interface.
See the task for screenshots.
- No longer makes users want to claw their eyes out.
- Every category is now linked to its description page, with the link color correctly reflecting page existence, which is much closer to MediaWiki and HotCat interfaces users are familiar with.
- Improved warning message about using non-existent categories is displayed on hover and immediately after a category is added.
- Categories that were preset or copied from first upload's details behave consistently with newly typed ones (rather than a mixture of input fields and removable capsules).
Depends on I66e603fd45b8d3fd61618f9115cd031f6fa01e9d in MediaWiki core.