[xmonad] darcs patch: Module for automatic placement of floating windows

[Quentin Moser]

After months of getting all my floating windows spawned in the top-left
corner and moving them by hand I finally broke down and wrote a
floating window module.

This module provides both a ManageHook and an X action to manually
trigger repositioning of the focused window, supports both
WindowArranger and "real" floating windows, and implements the usual
placement policies (smart, fixed position, under the mouse).

I haven't tested it extensively yet but everything I've tried to do
with it worked as intended. At any rate, comments are welcome if you
think there's something wrong with it.

Hope someone finds this useful!

Quentin