This commit moves user agent related functionality out of several
core libraries and combines it into a more manageable class.
All core uses are converted and functions deprecated in favor
of the new class.

This reverts commit af62237d.
This reverts commit 87a4194f.
This reverts commit b2c66eb6.

Conflicts:

	version.php

This reverts commit ab7632b7.

This commit moves user agent related functionality out of several
core libraries and combines it into a more manageable class.
All core uses are converted and functions deprecated in favor
of the new class.

The patch converts the dock into a YUI shifter module and at
the same time improves several aspects of its operation.
The features of this patch include:
* Dock Module conversion.
* A loader that ensures we don't include the dock JS or its
  requirements unless actually required.
* We no longer include the dock JS for themes that don't
  enable it.
* Blocks no longer add registration events to the page
  instead a dockable attribute is added to the html and the
  loader looks for that.
* The dock module is properly documented and running YUIDoc
  gives good quality documentation.
* We no longer need the dock module registration or
  subcomponent.
* All events that can be delegated are now delegated.
* Removed unused variables and code left over after fixes.
* Support for docking blocks renderered using the new blocks
  render method. Better support for custom block regions.

Petr Škoda authored Apr 10, 2013 and Damyon Wiese committed Apr 15, 2013

This patch is based on work by Gareth J Barnard, Pau Ferrer Ocaña (crazyserver) and others.

Only a problem when formatstringstriptags is disabled

This should allow us to switch page layout on admin pages and elsewhere before $OUTPUT->header() call.

MDL-28135 general Updating all hardcoded "docs.moodle.org/en/Development:" type doc links to "docs.moodle.org/dev/"