Support for hovering on cell's with state 

If parent row are hovered, child cell with state should react to this.
Fix popover when using append.
Add test for popover.
Fix #13138: use underscore prefix to ignore directories
Merge pull request #13167 from ZDroid/underscore

Fix #13138: use underscore prefix to ignore directories
Fixes #13079: Scope .open class in button variant mixin to immediate children
Merge branch 'master' of github.com:twbs/bootstrap
grunt
Fixes #13158: add link to nonresponsive docs in the example
fixes #9461 - Make carousel ignore non-items in carousel-inner
Fixes #13141: Add a max-width: 100%; to label elements so IE8 wraps text
Merge branch 'master' into fat-9461
grunt
Merge pull request #13173 from twbs/fat-9461

fixes #9461 - Make carousel ignore non-items in carousel-inner
grunt
Merge pull request #13165 from stefanneculai/master

Fix popover when using append
expand issue # ref to full URL
Merge pull request #13013 from ogonkov/patch-1

Support for hovering on cell's with some state
grunt
Fixes #13037: add text-align: left; to prevent alignment change in dropdowns