Add :ui zen module

This, combined with the new ':tools (lookup +dictionary)' feature will
eventually replace the ':app write' module.

init.example.el

@@ -42,6 +42,7 @@
        vi-tilde-fringe   ; fringe tildes to mark beyond EOB
        window-select     ; visually switch windows
        workspaces        ; tab emulation, persistence & separate workspaces
+       ;;zen               ; distraction-free coding or writing
 
        :editor
        (evil +everywhere); come to the dark side, we have cookies