Make use of FFOO_PRETTY_USAGE mode

src/bin/saturnin.skel

     inigrep_modules "$distd"
 }
 
-export FFOO_PATH FFOO_CONFIG_PATH SATURNIN_VERSION SATURNIN_CACHE_HOME
+export FFOO_CONFIG_PATH FFOO_PATH FFOO_PRETTY_USAGE \
+       SATURNIN_VERSION SATURNIN_CACHE_HOME
 
 FFOO_CONFIG_PATH="$(inigrep_paths | tr '\n' :)"
 FFOO_PATH="__SATURNIN_FFOO_DIR__"
+FFOO_PRETTY_USAGE="subcommand"
 SATURNIN_CACHE_HOME="__SATURNIN_CACHE_HOME__"
 SATURNIN_LIBEXEC="__SATURNIN_LIBEXEC__"
 SATURNIN_VERSION="__VERSION__"