[Xmonad] xmonad, now with workspace info in status bars

[Donald Bruce Stewart]

So after some nudging from Rob, and Spencer, I added proper state
logging to xmonad. If you set 'logging = True' xmonad will print its 
internal state to stdout on each state change.

Then, using an external client, you can parse this info (the full state
of the window manager!) and render it however you want. One use is to 
pretty print the workspace info into dzen, as if we had a built in
status bar.

There's a script in XMonadContrib now, scripts/xmonad-status.hs, which
implements an example StackSet parser/pretty printer for status bars.

Screenshots of workspace statusbars:

    http://www.cse.unsw.edu.au/~dons/tmp/xmonad-dzen-tags.png 
    http://omploader.org/file/rob-dzen-status.png

(the latter is a perl script Rob wrote, not in the repo yet).

You run this thing by piping the output of xmonad into the pretty
printer, e.g.

   xmonad | xmonad-status | dzen2 -ta l -fg '#a8a3f7' -bg '#3f3c6d'

We'll probably settle on a dwm/wmii-ish exapmle status bar to distribute
with xmonad.

-- Don