Allow to re-validate via systemd

[brada4]

Should be something like

ExecReload=/bin/kill -USR1 $MAINPID

In the unit file

[partim]

I’m not entirely sure, re-validation qualifies as a reload in the systemd sense since it doesn’t actually reload the config but really only triggers a validation run. For instance, if you change the RTR or HTTP listener configuration, that change will not be considered if you’d run systemctl reload routinator.

[brada4]

Currently reload is unused, just to fill it with something until the described full reload is implemented?
E.g apache reload is 'graceful' , one has too restart to add new module
Named reload in most cases is rndc relpad, i.e zone reload. I dunno, incomplete reload as opposed to restart seems acceptable around.