Fixes menubar scss mixins and adds new icon.
Removes unused ferret search lib.
Adds a complete callback for Alchemy windows.

The complete callback gets called after the window loaded its content.
Removes background image preloader jquery plugin.

It wasn't in use anyway.
Prevent default link event on element window's toolbar buttons.

Fixes an issue with Turbolinks always reloading the page while clicking on the element window's toolbar buttons.
Fixes Turbolinks issues with link overlay.
Removes unnecessary clipboard select helper and fixes select box css class.