Layout enhancements for listing specifications

- Slats expanded for status and workgroup data
- Fixed a spacing issue with the last item of .tightened link lists
- Add minimum width to drop menus
- First pass at <progress> bars styling in slats
- Additional icons for workgroup & status in slats and menus
- Fixed an error in Bartender that would be thrown if Sort menu item
was absent (state.sort would be undefined)

Related to issue #9