* Don't use body as tooltip container, allow notification area overflow
Badge tooltips are using container: 'body', so they can overflow the
notification area. When the user navigates back while a badge tooltip is
showing, the tooltip remains visible.
This commit removes the body container attribute and instead allows the
notificationDropDown to overflow, so badge tooltips aren't cut off.
Instead, this adds overflow: hidden to NotificationList.
Fixes#2118.
* Remove newline
- Get rid of Bootstrap (except we still rely on some JS)
- Use BEM class names
- Rework variables/theme config
- Fix various bugs, including some on mobile
The CSS is still not ideal – it needs to be cleaned up some more. But
that can be a focus for after beta.
