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`.
* Explicitly import pure, (<$>), (<*>) and (<$) from Control.Applicative.
* Use DeriveDataTypeable pragma.
* Remove type signature from pattern synonym.
Make 'stackMerge' safer by implicitly appending any leftover elements
rather than discarding them. Otherwise on refresh the missing windows
will be deleted. This is only necessary if the stack has been shortened
- i.e. not required by this module.
Minor miscellaneous documentation fixes.
