[xmonad] [patch] Added doShift function in ManageHook

[Don Stewart]

veselov:
> 
> Hi all!
> 
> While writing an article about xmonad, I've noticed that writing and
> explaining 'doF . W.shift' in manage hooks code is a bit obscure and
> cryptic for xmonad novices. So I've added doShift function, which has
> more user-friendly name and makes possible to avoid 'doF' function,
> which name might seem strange.

Applied, thanks.

-- Don