Specify `img` alternative text.
Expand caveat for disabled fieldsets and links
Redundant role="form" on <form>s
Redundant role="navigation" on <nav>s

plus one example that still used the old <div role="navigation"> and a
fix-up of the callout as per
https://github.com/twbs/bootstrap/issues/15109
add unit tests for Carousel's 'wrap' option
honor wrap option in Carousel.getItemForDirection; fixes #15144
Merge pull request #15129 from twbs/examples-img-alt

Specify `img` alternative text.
Merge pull request #15152 from twbs/fix-15144

honor wrap option in Carousel.getItemForDirection
[skip validator]
Merge pull request #15125 from patrickhlauke/docs-clean-up

Docs clean up - unnecessary role attributes, callout clarifications
Since Safari has released new fixed versions, we're unlikely to take any further action on this.
Fix name spelling
Merge pull request #15156 from Quy/master

Fix spelling of necolas' last name
Revert "Follow-up to #13074: use spec syntax instead of deprecated mixins"

This reverts commit b10b373c6019666dbe1152245c9efdf214ceaa6a.

Resolves #14937.
grunt
fix travis.yml lint errors
Merge pull request #15161 from twbs/travis-lint

fix travis.yml lint errors
add unit test for affix-top for padding issue
Fixes affix-top class not applying

Use scrollTop instead of colliderTop which uses the elements
offset().top, as the offset top does not account for padding.

This issue can be replicated by using a navbar-fixed-top and applying
relevant padding to the body. (A navbar-static-top with no padding on
the body does not encounter this issue)

Fixes #15078
Closes #15154 by merging it
Merge pull request #15154 from nickyod/affix-top-bug
Use npm instead NPM and update twbs team link.