Related to https://github.com/shaarli/Shaarli/issues/877
Plain grey links would lead to think that the link is somehow disabled/inaccessible/private
This slightly improves clarity/usability
* The tag list can be sort alphabetically or by most used tag
* Edit/Delete are perform using AJAX, or fallback to 'do=changetag' page
* New features aren't backported to vintage theme
* Add a checkboxes in linklist which display a sub-header containing action buttons
* Strongly rely on JS
* Requires a modern browser (ES6 syntax support)
* Checkboxes are hidden if the browser is old or JS disabled
* Add API settings in `configure.html`
* Fix textarea autoresize
* Load user.css from data folder
* Move fold/expand all button to the right and fix an issue with already folded items
* Reset datetime display to international datetime
* Temporarilly remove JS login panel (need improvement and integration with the plugin system)
* Body background is slightly lighter
* Fix an issue where thumbnails were hidden by description
* Fix an issue where private orange bar wasn't displayed with thumbnails
* Remove the gradient bar behind titles
* Fix empty bookmarklet name in Firefox
