Avoids cycling carousels when the page isn't visible.
Closes #17710
Refs #15566

We want to sum two numbers, not concatenate their stringifications.
Closes #17457 by merging a tweaked version of it.

When a DOM node is passed to an HTML tooltip, the `title` node is only
moved if it is not already in the tooltip. Otherwise, `empty()` is used
instead of `detach()` before appending the `title` to avoid memory
leaks. If a DOM node is passed to a plain text tooltip, its text is
copied via jQuery `.text()`.

Replaces `.detach()` with `.empty()`, as `.detach()` is almost never
useful but instead leaks memory. The difference between `empty` and
`detach` is that the latter keeps all the attached jQuery events/data.
However, since we do not return the previous children, the user would
have to keep these themselves, thus they can `detach()` if necessary.

This is a port of https://github.com/twbs/bootstrap/pull/14552 to v4.

fixes #17097: Go back to using jQuery's text and html methods since innerText is nonstandard and not present in Firefox

Closes #17272 by merging a tweaked version of it.

[skip validator]

add modal my gawd