* 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

* Clean up some utilities

- Align CSS properties
- In `_spacing.scss`, we had a comment saying what 'a' was for, but we removed that so this comment no longer applies

* Remove '-xs' from `.navbar-toggleable-xs` and remove duplication

* Fix outdated classes to use newer ones

* bower.json, package.json: Extend jQuery version ranges to include v3
* NuGet: Bump jQuery to v3.0.0.1
* Docs+Examples: Update jQuery to v3.0.0
* Use jQuery v3.0.0 for JS unit tests
* Update jqueryVersionCheck to allow jQuery v3.x.x

[ci skip]

[skip sauce]

Now that we don't support IE 8 it's safe to do that.

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

[ci skip]

Move them to footer, and remove duplicate ones.

[ci skip]

Shouldn't really happen, but China for example has blocked Google so this should help.

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

[ci skip]

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.

- Move example to correct location docs/examples/
- Move custom JS and CSS into stand-alone files
- Update headers and footers
- Copy-editing