Add nested kbd element styles for actual keys or inputs
Changed last-child to first-child
As noted by @jerem the first child will actually be the last shown
replace js scrollspy test for default behavior
add button to toggle the optional theme when viewing the docs; fixes #9764
regenerate minified docs JS & CSS
Fixes #13478, reverts #10941
Revert "Temporarily revert README deletions from #13470,"

This reverts commit 54284a13c6b503d925bf6f75db2830f1af7fcf98.
Merge branch 'master' into icon_paths

Conflicts:
	dist/css/bootstrap-rtl.css
	dist/css/bootstrap.css.map
	dist/js/bootstrap.min.js
	docs/dist/css/bootstrap.css.map
	docs/dist/js/bootstrap.min.js
Merge branch 'master' into icon_paths

Conflicts:
	dist/css/bootstrap.css.map
	docs/dist/css/bootstrap.css.map
Customizer: Alert on successful save to Gist
Adjust for Scrollspy offset when calculating maxScroll.
Add Scrollspy maxScroll with offset test.
Add tooltip self-reference to address #12320

primarily adds a data- attribute to the tooltip (and thus, the popover)
to create a self-reference.
Adds aria described by to tooltip plugin for accessibility

Generates a unique id for tooltip and adds [aria-describedby] to the element
it is called on. Resolves issue #13480

- set up test
- linted the code styles
- passed the tests
- integrated feedback from @cvrebert
add missing event namespacing in modal.js
Update showSuccess to use new classes
add to TRAVIS_COMMIT_MSG, TWBS_DO_VALIDATOR, TWBS_DO_SAUCE vars to Travis
Travis: skip RubyGems install+cache when TWBS_DO_VALIDATOR=0
Gruntfile: extract runSubset() func
Gruntfile: skip steps when $TWBS_DO_*=0