This patch improves the handing of new appearing windows for which only
a wildcard assignment - but no exact assignment - rule exists. In the
prior version, an interactively raised window would stay in front of
such a window, which is unintuitive. The new version applies the
to-front mechanism to unknown new windows. For known new windows (with
an exact assignment rule) their original stacking position is preserved.
This commit replaces the former floating_window_layouter with a new
window_layouter component that supports the subdivision of screen space
into columns and rows, the concept of layers, and the principle ability
to store window layout information across reboots. The latter is
accomplished by reflecting the component's internal state as a 'rules'
report to the outside.
Fixes#3031
