* Add variables for shades and tints of each major color

* getting-started/theming.md: use a `range`.

Now it should properly ignore the current published karma-browserstack-launcher versions

Bumps [terser](https://github.com/terser/terser) from 4.3.8 to 4.3.9.
- [Release notes](https://github.com/terser/terser/releases)
- [Changelog](https://github.com/terser/terser/blob/master/CHANGELOG.md)
- [Commits](https://github.com/terser/terser/compare/v4.3.8...v4.3.9

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [nodemon](https://github.com/remy/nodemon) from 1.19.3 to 1.19.4.
- [Release notes](https://github.com/remy/nodemon/releases)
- [Commits](https://github.com/remy/nodemon/compare/v1.19.3...v1.19.4

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [autoprefixer](https://github.com/postcss/autoprefixer) from 9.6.4 to 9.6.5.
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/master/CHANGELOG.md)
- [Commits](https://github.com/postcss/autoprefixer/compare/9.6.4...9.6.5

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Fixes dart sass compatibility.

Add optional `$color` argument to `button-variant()` and
`button-outline-variant()` for additional flexibility.

By the time v5 stable will be out, 8 will be EOL (December 2019).

This way we match the Travis CI behavior, and it's inherited by all steps.

* Scope .form-check-input layout to the .form-check parent

* Remove margin-bottom from list-group-items in case they are label elements

* document .form-check in input groups and list groups, and cleanup the no-label examples in the main .form-check docs

This section is meaningless and doesn't serve any purpose.

Without this, coveralls didn't receive the branch info thus leading to failures when we switched branches.

* Remove outline from select box in FF

* Use $form-select-color

Stack in cards in one column when < md