Merge branch 'stack'

[Thorsten Wißmann <edu _at_ thorsten _minus_ wissmann _dot_ de>]

Hi,

today I merged the stacking branch to master. This means that
herbstluftwm now actively maintains the stack of windows as follows:

On each tag there is an own stack of clients and there is one global
stack of monitors. The slice for each monitor only consists of the stack
of the tag, visible on that monitor, e.g.:

  +---------------------------------+
  | Monitor A with tag 1 | Client X |
  |                      | Client Y |
  +---------------------------------+
  | Monitor B with tag 8 | Client Z |
  |                      | Client W |
  +---------------------------------+

If the contents of monitor A and B are swapped then e.g. client Z would
be above of client Y. See also the STACKING section in the man page[1].

The stack also is printed by the stack command, which is neither final
nor documented yet.

Currently there is a known bug if e.g. client Z is in fullscreen, which
is already described in the BUGS file. It still works better than before
so we probably have to live with that (because there is no clean or
fully working solution).

If you notice further bugs, please report them. My hope is to release
v0.4 within the next few days.


Thorsten

[1] http://wwwcip.cs.fau.de/~re06huxa/herbstluftwm/herbstluftwm.html#STACKING