Features:
+* delay activation of logind until somebody logs in, or when /dev/tty0 pulls it
+ in or lingering is on (so that containers don't bother with it until PAM is used). also exit-on-idle
+
* cache sd_event_now() result from before the first iteration...
* remove Capabilities=, after all AmbientCapabilities= and CapabilityBoundingSet= should be enough.