[Xmonad] Changes in the dev branch: xmonad can now be configured without recompiling the src!

[Don Stewart]

Just an update on what's been happening in the development branch of
xmonad. This is a quick summary of changes that will affect those who
follow the darcs branch.

The big merge is done, thanks to David for prototyping, and Spencer for
kicking the types into shape!  xmonad from darcs now builds as a
library, as does the extension library.

The (very) good news:
    * xmonad can be reconfigured without having to recompile the source!
    * multiple xmonad instances on a system can use different config settings
    * the contrib library builds as a normal library
    * Config.hs now lives in ~/.xmonad/xmonad.hs
    * configuration is now much simpler and shorter. My 100 line
      Config.hs is now around 5 lines, with the same result

in particular point one was the key technical issue which made xmonad 
not quite a first class citizen on unix -- it had to be recompiled to be
reconfigured. Those days are now passed.

The bad news:
    * the format and location of Config.hs has changed slightly, 
    meaning you'll have to edit your ~/.xmonad/xmonad.hs if you 
    follow the darcs branch (and the upcoming 0.5 release)
    * documentation is now a little out of date.
    * xmonad now requires Cabal 1.2, which you can get with ghc 6.8,
    or from hackage.haskell.org

Some initial examples of the ~/.xmonad/xmonad.hs configuration 
system are appearing on the wiki,

    http://haskell.org/haskellwiki/Xmonad/Config_archive

and if you port your old Config.hs across to the new xmonad.hs style, 
please consider uploading both old and new to the wiki, to make it
easier for others.

Other documentation is likely to be out of date. If people have
suggestions on how best to migrate users from the old to the new
configuration system, I'd love to hear it. 

-- Don