Adds new dark skin. Public Beta

Bootstrap grid system is now available to Adminimal Themers.

* Improved styling of material skin forms and fieldsets.

git commit -m 'Issue #2653436: Theming bug with Fast Permissions
Administration (FPA)'

* Improved fieldset top border. Replaced with top box shadow to avoid
triangle shaped corners rendering within browsers. Suggested by "Stavros
Ioannidis"

+ CKEditor Adminimal style is now optional and can be enabled/disabled
from the settings page. See #2662406
* Renamed ckeditor.css to ckeditor-adminimal.css . See
#2662406#comment-10866646

* Features module style improvements
* Translation interface style improvements
* Devel debug strong tag style improvement

* Issue #2589075 by shadysamir: Sticky form actions extend outside
viewport in RTL
* Improved right sidebar fixed positioning in module filter.

* Fixed module filter sidebar fixed positioning. Bug reported by @nchar
and @h.papazoglou from Netstudio.gr
* Alternative skin improvements
* Improved last patch fixing top border

* Improved "Feature" module styling

+ Added sticky fixed positioning option for action links
+ Added animation to the text input elements on focus.

+ New skin “Alternative”. Slightly different than the original skin.
* Fixed positioning of radio and checkboxes labels in OSX by 2 pixels
in default skin.
+ Added transition animation to the table row hover background
hilighting.
* Fixed top margin of action buttons in the system action page.

* Fixed Views left and right sidebar display issue reported by @ReBa see
#2562275

- Unset hidden region

+ Added setting to disable rounded corner styling for action links. See
Issue #2551499: Revert to the skin of 7.x-1.21 (without rounded buttons)

* Issue #2545714 by @drumm: Disabled submit buttons should look disabled
* Green button for commerce discount

* Issue #2550631 by earlofsandwich: Dropdown icon on inline entity form
overlaps content
* Added some margin for the draggable table weight toggler

* Issue #2552713 by dubcanada, ANDiTKO: Issue with Drupal Commerce and
new Form Radios
* Improved coloring and styling for few commerce buttons

* Issue #2553985 by mqanneh, ANDiTKO: Broken style for checkbox with red
style
* Issue #2554715 by RAFA3L, ANDiTKO: Checkbox when using Location Module
* Improved Grey button hover styling
* Improved all button click (:focus) styling

This reverts commit 2dc51fff.