fix nav links to end with / to avoid 301 redirect
Merge pull request #14472 from mrduguo/master

fix nav links to end with / to avoid 301 redirect
mention #14320 in browser bugs
grunt
Document that input groups weren't intended for use with <textarea>s

Refs #14362
Merge pull request #14482 from twbs/doc-14362

Document that input groups weren't intended for use with <textarea>s
Gruntfile.js: Simplify copy task.
Merge pull request #14488 from vsn4ik/gruntfile_copy_task

Gruntfile.js: Simplify copy task.
Update grunt-jscs.
Fixes #14443: Only transition what needs transitioning for thumbnails to avoid Safari/Chrome render bug
Collapse accessability

Added tab-role, aria-selected, and aria-controls into the collapse html
docs.

Added support for toggling aria-expanded, aria-selected, and
aria-hidden via the javascript collapse events.

References issue #13555.

Sweet example at
http://accessibility.athena-ict.com/aria/examples/tabpanel2.shtml