[xmonad] non-layout layouts

[Devin Mullins]

In XMonadContrib, XMonad.Layout.*, suggest the following moves:
  LayoutModifier   -> Util
  WindowNavigation -> Action
  WorkspaceDir     -> Util

Thoughts?

Also, Util contains a mix of internal utils for contrib devs (Invisible,
XUtils), and utils for end-users (Dmenu, EZConfig). Is this a problem?