Fix hover-popover/tooltip flickering when mouse re-enters

Created by: sgonyea

I'm not exactly happy with the code change I've made to fix this issue, but this at least demonstrates a fix (as well as the bug itself).

JSBin: http://jsbin.com/hajeta/2/

Issues:

• Mouse out / mouse in over elements within the popover, the popover will continually flicker (until your mouse hovers over only the popover itself. no child elements)
• Mouse out / mouse in, if the user scrolled within the popover -- that scorll position is lost (b/c the popover is recreated repeatedly)

Steps to trigger the flickering bug:

• Hover over the text "Hover here!"
• Mouse over the tooltip itself
• Mouse-out and then quickly mouse back in (specifically, mouse back in over the text itself)
• See a flicker. Then mouse up over other text. The flickering continues.

Additionally: You can scroll within the popover and see the flicker / (continual) resetting of the inner scrollbar position.

Hopefully the explanation and the demo make sense.

Thank you very much! Bootstrap is fantastic.