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`.
This module provides a way to query the session startup.
Currently the flag has to be set by calling setSessionStarted in
the startupHook. The goal would be to merge this into xmonad at some
point and set the flag when the state file is read in, and remove the
need to manually set it.
