xwm: stack below on map
xwm: stack below on map

Since xwm only manipulates the stack when focusing a window, newly
mapped windows should be stacked below the focused window. This prevents
the newly mapped window from stealing focus due to being on the top of
the stack.

ascent12/wlroots,swaywm/wlroots,SirCmpwn/wlroots,ascent12/wlroots,swaywm/wlroots