This is a convenience module in order to have less import noise. It
re-exports the following:
a) Commonly used modules in full (Data.Foldable, Data.Applicative, and
so on); though only those that play nicely with each other, so that
XMonad.Prelude can be imported unqualified without any problems.
This prevents things like `Prelude.(.)` and `Control.Category.(.)`
fighting with each other.
b) Helper functions that don't necessarily fit in any other module;
e.g., the often used abbreviation `fi = fromIntegral`.
The ppVisibleNoWindows was added in #241 but none of the modules that
rename/mangle workspace names were updated (or didn't exist at the
time). This fixes this.
Related: https://github.com/xmonad/xmonad-contrib/pull/241
Related: 670eb3bc605b ("Added pretty printer for empty visible workspaces")
