* Remove IE compatibility mode meta tag from docs, examples, and JS tests as we no longer support IE9 and IE8
* update and remove some IE bits from our supported browser page
* update introduction.md to match
* reword starter template intro

update justified nav to use justified navbar; remove safari bug warning given flexbox implementation

flip things around again, no more base class, try out some new stuff to keep responsive flex grid working

Fixes potential problems with iOS9's new viewport behavior - see for
instance https://forums.developer.apple.com/thread/13510

Move them to footer, and remove duplicate ones.

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Document in the source code that the justified nav is meant for single line list items only. This should help prevent Issues like #15906 in the future.

Fix issue #15601 — Position of X-UA-Compatible, charset and viewport

Add comment to all examples

The non-responsive is correctly saying 2 instead of 3

plus one example that still used the old <div role="navigation"> and a
fix-up of the callout as per
https://github.com/twbs/bootstrap/issues/15109

Closes #14951 by merging it.

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This way, it works in all browsers.

The validator doesn't choke anymore on this and even though it's not spec compliant, it's needed for some IE versions. So until we move favicon.ico in root, this should do the job.

Closes #13379.

- Implements new format "Copyright 2011-xxxx Twitter, Inc.", which resonates well with our History page and more accurately reflects the copyright status of the repo
- grunt dist to update all the files