change definition of 'description' function for LayoutModifier so an extra space is not added if the modifier description is empty.
change definition of 'description' function for LayoutModifier so an extra space is not added if the modifier description is empty.

darcs-hash:20071018183054-bd4d7-0a1a4a2fb97cf789106b0e820b0471ea9f33146a

yzhou61/xmonad-contrib,yzhou61/xmonad-contrib,yzhou61/xmonad-contrib