Switch default mode to `stacked`

Finally stop: painstakingly changing it manually for every new workspace
ever.

(...for no reason; just something in my brain preventing me to add
this line for ~4 years.)

dotfiles/config/bmo/wish.ini

     idos    = http://jizdnirady.idnes.cz/vlakyautobusy/spojeni/
     idosbrq = http://jizdnirady.idnes.cz/brno/spojeni/
     jnoise  = https://mynoise.net/NoiseMachines/jungleNoiseGenerator.php
+    kam     = http://www.kam.vutbr.cz/?p=otdo
     kb      = https://keybase.io/netvor/
     kbfs    = https://keybase.pub/netvor/
     ma      = http://www.mapy.cz/

dotfiles/i3/config

 mouse_warping none
 hide_edge_borders vertical
 font pango:Inconsolata 12
+workspace_layout stacked
 
 # change focus
 bindsym $mod+h              focus left