[xmonad] Patch: improved support for replacing an existing window manager

[Adam Vogt]

For reference, I've added to contrib the module XMonad.Util.Replace,
which seems to work as well as these core patches, other than the lack
of command line flag support (the xmonad binary does not pass flags
other than --resume to the ~/.xmonad/xmonad-$arch-$os).

Any suggestions for addressing that problem (or the alternative of
running `~/.xmonad/xmonad-$arch-$os --replace' instead of
/usr/bin/xmonad)

        Mon Oct 12 01:23:06 EDT 2009  Adam Vogt <vogt.adam at gmail.com>
        * Add U.Replace which implements a --replace behavior.

* On Thursday, September 17 2009, Jan Vornberger wrote:

>Hi there!
>
>First patch from Bluetile's repository for consideration to go into
>xmonad mainline. This is the original patch (see
>http://osdir.com/ml/xmonad@haskell.org/2009-05/msg00010.html) plus two
>more patches, which
>
>  * make this take effect only if the '--replace' flag is given
>  * add a config option 'alwaysReplace' to override the --replace flag
>
>Best regards!
>
>Jan

>Sat Apr 18 00:25:09 CEST 2009  Jan Vornberger <jan.vornberger at informatik.uni-oldenburg.de>
>  * half-implemented support for replacing an existing window manager
>
>Thu Sep 17 20:47:14 CEST 2009  Jan Vornberger <jan.vornberger at informatik.uni-oldenburg.de>
>  * Only replace existing window manager when given '--replace' flag
>
>Thu Sep 17 20:56:56 CEST 2009  Jan Vornberger <jan.vornberger at informatik.uni-oldenburg.de>
>  * Add config option 'alwaysReplace' to replace window managers regardless off --replace flag