remove 'command cat' from a few places
support for --host, --global, --system on various commands

This affects edit, append, show, delete, filename, and template install.
When specified, operate on the indicated script
run all scripts, including new per-host ones

Run order (for both leave and enter) is:

1) Run system-wide global script
2) Run system-wide host-local script
3) Run user's global script
4) Run user's host-local script
update completion to support --host, --global, --system