fixes #13216

change `@zindex-popover` and `@zindex-tooltip` values to be greater than
those set for `@zindex-modal` allowing tooltips and popovers to be
displayed in front of modals (and all other content).
Fix carousel control margin asymmetry
document that you have to add .active yourself on prechecked btn-ized checkboxes+radios; fixes #12651
Update dependencies.
Fix the new JSHint warnings.
Run `grunt`.
add timing logic+output to s3_cache.py
grammar
Travis: introduce $GEMDIR env var
doc how to change the collapsed mobile navbar breakpoint; fixes #13126
move some caching info+logic out of .travis.yml; fixes #13136
better way of tracking what caches need to be uploaded; fixes #13270
customizer: squelch error when can't save Gist
Replace $.fn.bind with $.fn.on in alert docs
replace $.bind() with $.on() in unit tests; per #13272
Re-implement Universal Analytics

X-Refs:
https://github.com/twbs/bootstrap/commit/b2a67ffe55f5fedb0ae1d5dff331687c3e744be0
https://github.com/twbs/bootstrap/commit/c97e6d5cad74d20257d28734f85311ef5d00b560
fix grammar in "Underlined text" example
Fixed typo in Responsive Tables CSS docs
#12790: Add link to unofficial Italian translation
grunt dist