[dwm] urgent color patch

Hi there,

first of all dwm is great (big thanks to all of you), but i don't really
like the way it handles urgent windows. Just reverting the fg/bg colors of
the tag in the statusbar can be a bit confusing (changing the selection
colors).
For those who are interessted I wrote a (very) small patch which adds an
"urgent color" (+3 sloc). It is much more striking if the tag is changed to
another color especially when using an imessenger like pidgin which sets
unread message windows urgent.

i'm new to c, so if there's a better way let me know

regards,

daniel