[Xmonad] Darcs patch [1/2]: Implement screen map for physical monitor order not matching Xinerama order

Implement screen map for physical monitor order not matching Xinerama order The internal screen numbering scheme used by Xinerama is arbitrary and may not match the physical order of monitors as attached by the user. This can lead to the mod-w/e/r switch hotkey doing the switches in a nonintuitive way. This patch implements a mapping that allows correcting this ordering in a central place, rather than modifying the key bindings directly. See also: separate DynamicLog patch to fix the Xinerama format display to match [ This is my first attempt at using darcs, and also at writing Haskell, please give me feedback if I'm doing this wrong! ]