Correctly selects arrow placement for a tooltip

Fixes #13696.
Fixes #13696.
Fixes #14197.
Closes #13718.
grunt
README.md: Add npm install info.
Update github links in footer.
Merge pull request #14612 from vsn4ik/update_docs_links

Update github links in footer.
Merge pull request #14611 from vsn4ik/add_install_with_npm

Add npm install info.
modal docs: ensure all <button>s have an explicit `type` attribute

[skip sauce]
Merge pull request #14624 from twbs/type-button

modal docs: ensure all <button>s have an explicit `type` attribute
Must explicitly destroy tooltip in SVG unit test since its container is body.

Leaking tooltips across tests leads to confusion and sadness.
Merge pull request #14625 from twbs/svg-tooltip-test-fix

Must explicitly destroy tooltip in SVG unit test since its container is body
Use container instead of parent for tooltip/popover auto-placement calcs

Fixes #14561. Big thanks to @wickstargazer.

[skip validator]