* renames `select-box-kit` into `select-kit`
* introduces `single-select` and `multi-select` as base components
* introduces {{search-advanced-category-chooser}} as a better component for selecting category in advanced search
* improves events handling in select-kit
* recreates color selection inputs using {{multi-select}} and a custom {{selected-color}} component
* replaces category-selector by a component using select-kit and based on multi-select
* improves positioning of wrapper
* removes the need for offscreen, and instead use `select-kit-header` as a base focus point for all select-kit based components
* introduces a formal plugin api for select-kit based components
* introduces a formal pattern for loading and updating select-kit based components:
```
computeValue()
computeContent()
mutateValue()
```
To achieve replacement, this commit also adds support for:
- clearSelectionLabel which will allows to unselect any chosen category
- select-box inside a modal
- fixes minor css positioning issues
Note: {{category-chooser}} will be removed in the next weeks.
Note this commit leaves out the biggest occurrence of the editor
which is the post/topic composer.
To avoid major breakage, this replaces it everywhere else it was
used:
* User preferences (About Me)
* Admin Customizations > Text Content
* Category Templates
* Editing Queued Posts
A future commit will replace the main composer with this editor
and will remove the unused pagedown code.
Guo Xiang Tan
Tim Lange
Guo Xiang Tan
Maja Komel
Sam
Joffrey JAFFEUX
Robin Ward
Neil Lalonde
Régis Hanol