2.0.0.0-dev41

* All-new look & feel of backend UI -- "Magento 2 backend" theme
  * This theme includes "Magento User Interface Library" -- a set of reusable CSS-classes, icons and fonts
* Theme editing features (in backend UI):
  * Ability to view static resources, such as CSS and JavaScript files, which are inherited by virtual themes from physical themes and application, and library
  * Ability to upload and edit custom CSS/JavaScript code assigned to a particular virtual theme
  * Ability to manage image and font assets for virtual themes
  * The uploaded or edited theme resources are used in page generation
  * Ability to rename virtual themes
  * Physical themes are read-only
* Visual design editor:
  * Ability to enter a "Design Mode" directly from the list of "My Customizations" in "Design Gallery"
  * Updated styling of theme selector and VDE toolbars
* Added functional limitations (managed through configuration files):
  * Ability to limit maximum number of store views in the system
  * Ability to limit maximum number of admin user records in the system
* Introduced mechanism of early discovery of memory leaks in integration tests:
  * Added ability to integration testing framework to detect usage of memory and estimate memory leaks using OS tools outside of PHP process
  * Also ability to set memory usage threshold which would deliberately trigger error, if integration tests reach it
* Refactoring in integration tests:
  * Broke down `Magento_Test_Bootstrap` into smaller testable classes
  * Minimized amount of logic in `bootstrap.php` of integration tests
  * Factored out memory utility functions from memory integration tests into a separate helper
  * Removed hard-coding of the default setting values from `Magento_Test_Bootstrap` in favor of requiring some crucial settings
  * Fixed integration tests dependency on `app/etc/local.xml`, changes in which were involved into the sandbox hash calculation `dev/tests/integration/tmp/sandbox-<db_vendor>-<hash>`
* Improvements in JavaScript widget "Suggest" (`pub/lib/mage/backend/suggest.js`):
  * Added ability to set callback for "item selection"
  * Added ability to provide a template in widget options
  * Implemented "multiple suggestions" ability directly in this widget and removed the "multisuggest" widget
* Converted several grids in backend from PHP implementation to declarations in layout
* Other various improvements:
  * Factored out logic of handling theme images from `Mage_Core_Model_Theme` into `Mage_Core_Model_Theme_Image`
  * Ability to filter file extensions in uploader component
  * Publication of resources linked in CSS-files will only log error instead of crashing page generation process
* Bug fixes:
  * Fixed several memory leaks in different places, related with dispatching controller actions multiple times in integration tests and with excessive reference to `Mage_Core_Model_App` object
  * Fixed integration test in `Mage_Install` module that verifies encryption key length
  * Fixed DHL shipping carrier declaration in config that caused inability to use it with shopping cart price rules
  * Fixed issues in generating of configurable product variations when the button "Generate" is invoked second time
  * Fixed an error that caused inability to create a theme in Windows environment in developer mode
  * Fixed various errors in JavaScript tests for visual design editor
  * Fixed broken "Edit" link on backend product management page