panel: Do not use dark theme anymore by default
applets/menu-window: Greatly reduce horizontal size

We now ellipsize labels over 35 characters in length, massively reducing
the amount of horizontal space required by the menu window.
panel: Fix menu padding (left)
panel/popover: Fix tail point for x=0
applets/clock: Include space for margin sizing
applets/menu-window: Visual fixups

We now use the symbolic shutdown icon, and a search entry in the
top of the menu window, similar to Chrome OS's menu window.
Icons have been enlarged, now that our window does not take up as
much space. The default style provided by budgie-panel's css
forces the GtkSearchEntry style to blend in with the popover.

As and when compatible themes appear, this can be changed.
applets/menu-window: Use more human text
Add hover style for panel launcher icons
wm/plugin: Remove deprecated API use (workspaces in 3.11)
Merge remote-tracking branch 'upstream/master'