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.

Fortify against bad characters in URLs.  This also makes www print one
URI per line (which was intended in the first place).

Scripts are supposed to be launched as sub-commands of /bin/saturnin, which
can easily handle this for them.

Or you can still set these variables by hand.  (i.e. `FFOO_DEBUG=true saturnin-www`)