[dwm] slave window + columns/rows layout

Hi all,
back from holidays I get some minutes to customize release 0.8 to fit
my weird thinking (i.e. a really dynamic screen layout)

Apply attached diff, then open a few terminals and press Mod1-t to
toggle between a master column and a master row. You can resize master
client with Mod1-b and Mod1-n

Some extra info here: http://wiki.mad.mw/dwm/JrPatchSet (home of the
infamous AWK script)

regards,

-- 
Julián