Merge branch 'master' into v4

Conflicts:
	_config.yml
	dist/css/bootstrap-theme.css
	dist/css/bootstrap-theme.css.map
	dist/css/bootstrap-theme.min.css
	dist/css/bootstrap.css
	dist/css/bootstrap.css.map
	dist/css/bootstrap.min.css
	dist/js/bootstrap.min.js
	docs/_includes/components/thumbnails.html
	docs/_includes/css/forms.html
	docs/_includes/css/grid.html
	docs/_includes/customizer-variables.html
	docs/_includes/footer.html
	docs/_includes/getting-started/download.html
	docs/_includes/getting-started/template.html
	docs/_includes/js/overview.html
	docs/_includes/js/popovers.html
	docs/_includes/js/tooltips.html
	docs/assets/css/docs.min.css
	docs/assets/js/customize.min.js
	docs/assets/js/raw-files.min.js
	docs/assets/js/src/customizer.js
	docs/dist/css/bootstrap-theme.css
	docs/dist/css/bootstrap-theme.css.map
	docs/dist/css/bootstrap-theme.min.css
	docs/dist/css/bootstrap.css
	docs/dist/css/bootstrap.css.map
	docs/dist/css/bootstrap.min.css
	docs/dist/js/bootstrap.js
	docs/dist/js/bootstrap.min.js
	docs/examples/navbar-fixed-top/index.html
	docs/examples/navbar-static-top/index.html
	docs/examples/non-responsive/index.html
	docs/examples/theme/index.html
	grunt/configBridge.json
	less/alerts.less
	less/badges.less
	less/jumbotron.less
	less/panels.less
	less/tables.less
	less/theme.less
	less/variables.less
	package.json
	scss/_button-group.scss
	scss/_buttons.scss
	scss/_forms.scss

scss/_buttons.scss

@@ -102,7 +102,7 @@
   &:hover,
   &:focus {
     color: $link-hover-color;
-    text-decoration: underline;
+    text-decoration: $link-hover-decoration;
     background-color: transparent;
   }
   &:disabled,