README.md: Аmendment links to use HTTPS.
Use single .dropdown-menu
Merge pull request #14382 from vsn4ik/https_links_in_readme

README.md: Change links to use HTTPS
Fixes #13943 again: lighten links, and text, in navbar. Still not 100% compliant, but it's better.
Merge branch 'master' of github.com:twbs/bootstrap
grunt
fixes #14441
fixes #14425: remove invalid css property
Merge pull request #14408 from vsn4ik/dropdown_menu_disabled_style

Refactor dropdown.less. Optimize ".dropdown-menu > .disabled" selector.
Fixes #14386: Reset font, text, and line-height properties in popovers
Full grunt
Merge branch 'master' of github.com:twbs/bootstrap
grunt