[Xmonad] Spiral.hs description

[Don Stewart]

byorgey:
>    A simple patch for Spiral.hs to provide a non-default implementation of
>    the description function in the LayoutClass instance.  Now the layout will
>    be displayed (e.g. by DynamicLog)  simply as 'spiral' rather than the
>    unwieldy default, 'spiralwithdir east cw (1%1)' or something similar.
> 
>    -Brent

Well spotted. Applied.