Clickover plugin not compatible with bootstrap 3

The [clickover](https://github.com/lecar-red/bootstrapx-clickover) plugin has not been updated in a year and is not compatible with bootstrap 3. (See, e.g. #3424)
I think I understand the reasoning in the PR code. Bootstrap triggers the `shown` event before the `click` event propagates up to the document level. Thus, when the user first clicks on the trigger, this handler is called after the `shown` event. In that case, we clearly don't want to hide the popover, despite the fact that the click was not inside of the popover. Still seems like there's a problem in the logic though; it's just a bit tricky to find the right workaround.