systemctl: remove systemctl sources, to be replaced by new script
manager: truncate manager_setup_signals() accordingly
man: systemd: cut down signal table and fix unit type count
man: systemd: document fifoctl and fifoout
system.conf: cut watchdog options
man: systemctl: rewrite so as to reflect new script
systemctl: implement first batch of commands (those w/o arguments)
systemctl: add fifoctl existence check (doesn't actually check if it's specifically a FIFO)
cgroup: don't migrate PIDs for slice units
man: systemctl: cleanups and clarifications