Remove unused imports in IPython.utils
Remove unused imports in IPython.extensions
Remove unused imports in IPython.html
Remove unused imports in IPython.kernel
Remove unused imports in IPython.qt
Remove unused imports in IPython.terminal
Remove unused imports in IPython.testing
Fix test import
Added relative import of RevealExporter to __init__.py inside exporters module.
Added another missing import inside transformer module.
Merge pull request #3520 from damianavila/import_reveal

Added relative import of RevealExporter to __init__.py inside exporters module
Merge pull request #3514 from minrk/ui-state-disabled

use bootstrap `disabled` instead of `ui-state-disabled`
Exclude frontend shim from docs build

Closes gh-3517
Allow specification of full highlight class in CSSHTMLHeader
Merge pull request #3523 from takluyver/docs-exclude-frontend

Exclude frontend shim from docs build

Closes #3517

The API doc writer has separate exclude patterns for modules and packages, so frontend needed to be listed in the modules exclusions.
Merge pull request #3516 from jakevdp/configurable_highlight

make css highlight style configurable
use `isoformat()` in jsonutil

allows preservation of timezone info.

Timezone info is still ignored in the extract-dates part, for now.
add IPython.utils.tz

Basic support for tz-aware UTC methods on date time objects.

The raw `utcfoo` methods still produce naïve objects,
so they are wrapped in a simple zero-offset tz-aware object.

This allows jsonutil to publish the timezone info,
eliminating the ambiguity of naïve timestamps (Firefox assumes local time, WebKit UTC).
add timezone info to `last_modified` in notebook managers

now Firefox won't get confused, turning utc timestamps into local times.

closes #3396
Add test for storemagic