[Xmonad] Removing the X11-extras dependency

[Don Stewart]

isaacdupree:
> Don Stewart wrote:
> >However, this is a big change, so bumping A.B has been done. And
> >1.3.0 > 1.2.3, so that's fine, according to
> >
> >    http://haskell.org/haskellwiki/Package_versioning_policy
> >
> >Thanks for raising this.
> 
> Yup.  Should it be 1.3.0.0 then?  (I'm not sure quite what's going on 
> with that "number of zeroes" issue most recently)

The minor-minor numbers appear optional from my reading. Only A.B.C are
required.