The previous version actually meant "create backup config.mke"

To maintain safety of colision and reflect purpose ('ffoo/saturnin_www.sh'
vs. 'libexec/saturnin-www.sh'), adding prefix 'saturnin_'.

No need to maintain module for one function; moved to saturnin-www; the
only user so far.

Config files can now be merged from 4 sources:  distribution-provided,
(share folder), local (/etc/saturnin), user-specific (~/.saturnin and
~/saturnin/ini.d/*)

Paths are transferred by saturnin meta-command so there's no need
to build sub-command binaries

Move cub-command to libexec path to prevent calling them directly,
allowing for better control of environment.