Implement Split View Menus

Split View Menus:

* Remove temporary menu items
* Add Split view icon w/tooltip
* Change Split view icon state based on split view scheme
* Create permanent menu
* Localize menu strings
* Fix gear menu so it's always at top of sidebar, add tooltip

cc @JeffryBooher 

This should be an ID so selector matching is much faster.  Same with the working-set-option-btn; We only have 1 and we only need 1 so there's no reason it needs to be a class.  Plus we can attach the menu to a click event using the ID selector which is universal.