Merge usage and help to --help

Be nicer to people who get help by trial and error.

src/shellfu/saturnin.sh

 }
 
 saturnin__help() {
-    #
-    # Print simple help message (basically just list of commands)
-    #
-    {
-        echo "built-in commands:"
-        echo "    conf"
-        echo "    help"
-        echo ""
-        echo "installed commands:"
-        saturnin__lssc \
-          | sed -e 's/^/    /'
-    } | mkhelp -E -f -
-    return "$EXIT_OK"
+    saturnin__usage --wanted
 }
 
 saturnin__lssc() {
     #
     # List subcommands
     #
+    echo conf
     find "$SATURNIN_LIBEXEC" \
         -mindepth 1 \
         -maxdepth 1 \
     while true; do case $1 in
         -d|--debug)     export PRETTY_DEBUG=true; shift   ;;
         -v|--verbose)   export PRETTY_VERBOSE=true; shift ;;
+        -h|--help)      saturnin__help; exit              ;;
         --version)      saturnin__version; exit            ;;
         --version-semver) saturnin__get app-version ;;
         --saturnin-get-*) saturnin__get "$1" ;;
     debug -v SHELLFU_PATH SATURNIN_LIBEXEC SATURNIN_CONF_PATH
     case "$subcommand" in
         conf)               saturnin__conf "$@" ;;
-        help)               saturnin__help ;;
         _ls_subcommands)    saturnin__lssc ;;
         _lsfun)             shellfu-get lsfun ;;
         _lsmod)             shellfu-get lsmod ;;
     debug "\$*='$*'"
     test -x "$binpath" || {
         warn "invalid sub-command: $subcommand"
-        saturnin__help
-        return "$EXIT_USAGE"
+        saturnin__usage
     }
     SATURNIN_SUBCOMMAND="$subcommand" "$binpath" "$@"
 }
 
 saturnin__usage() {
-    mkusage "[-d|-v] command [args...]" \
-            "help" \
-            "--version"
+    local es_param      # exit-status related arguments
+    test "$1" == "--wanted" && es_param="-e 0"
+    #shellcheck disable=SC2086 disable=SC2046
+    mkusage $es_param                                       \
+            "[options] COMMAND [ARG...]"                    \
+        -o                                                  \
+            "--debug    turn on debugging"                  \
+            "--help     show this help message and exit"    \
+            "--verbose  turn on verbosity"                  \
+            "--version  show version and exit"              \
+        -c                                                  \
+            $(saturnin__lssc)
 }
 
 saturnin__version() {

tests/cli/oracle/usage.stderr

 usage:
-  satcmd [-d|-v] command [args...]
-  satcmd help
-  satcmd --version
+  satcmd [options] command [args...]
+
+options:
+  --debug    turn on debugging
+  --help     show this help message and exit
+  --verbose  turn on verbosity
+  --version  show version and exit
+
+commands:
+  conf
+  dump
+  echo