Since a previous change combined all displays into a single file, it is
no longer necessary to create many temporary configs. The latest config
can just be dumped to the standard path so that running `waybar` on it's
own will load it.
If a config is selected for which the displays do not exist, either bail
or if in recovery mode, restore 'detached'. The latter was added in
anticipation of the swayidle script which will attempt to restore a
layout that may no longer be possible. Since swayidle disables dpms, it
must allow a backup display to come live if the last logged layout is
not possible.
John Mertz