allow _journalctl to work when the rcquotes option is set, broken in ba89f80620.
allow the completion of --file multiple times, which ba89f80620 claims is true.
Fixes#4842
Escape unit names for the eval call in _call_program
The value of the Id property is transformed back into a unit name
usable by systemctl.
system-systemd\x5cx2dcryptsetup.slice -> system-systemd\x2dcryptsetup.slice
Also filter units by property via parameter expansion, not a for loop
llua