tmpfiles.d: put default value of all for kill-who
control-response-util: add get_kill_who()
control-response-util: add get_kill_signal()
control-request: add kill
control-request: print error code when snapshot creation fails
control-request: functional cancel-job
control-request: add some breaks where applicable
control-request: add mdump that sends SIGUSR2 to self, use later for commands like 'show'
unit: fix indentation in merge_dependencies()
control-request: add list-dependencies