New sections are added: PAM options, crypttab options, commandline
options, miscellaneous. The last category will be used for all
untagged <varname> elements.
Commandline options sections is meant to be a developer tool: when
adding an option it is sometimes useful to be able to check if
similarly named options exist elsewhere.
Much like logind has a client in loginctl, and journald in journalctl
introduce timedatectl, to change the system time (incl. RTC), timezones
and related settings.