Do not show all modules/functions by default (add `-a` option)

src/bin/shellfu-get.skel

     #
     # List functions from module $1 or all
     #
-    shellfu _list_functions "$modspec"
+    local modspec="$1"
+    if $show_hidden;
+    then
+        shellfu _list_functions "$modspec"
+    else
+        shellfu _list_functions "$modspec" \
+          | grep -v ^_ \
+          | grep -v \\._
+    fi
 }
 
 do_lsmod() {
     # List available modules
     #
     local modspec="$1"
-    shellfu _list_modules "$modspec"
+    if $show_hidden;
+    then
+        shellfu _list_modules "$modspec"
+    else
+        shellfu _list_modules "$modspec" \
+          | grep -v ^_
+    fi
 }
 
 do_path() {
 
 main() {
     local action="usage"
+    local show_hidden=false
     local include=""
     while true; do case "$1" in
         --version)                  do_version;         exit ;;
         --version-semver)           do_semver;          exit ;;
         -I|--include)               include="$2";       shift 2 || usage ;;
+        -a|--all)                   show_hidden=true;   shift ;;
         -d|--debug)                 SHELLFU_DEBUG=true; shift ;;
         catfun|lsfun|lsmod|path)    action="$1";        shift; break ;;
         *) usage  ;;

tests/shellfu_api/TF_RUN

 . "$TF_DIR/include/tools.sh"
 
 shellfu_get_sorted() {
-    shellfu-get "$1" | LC_ALL=C sort
+    shellfu-get -a "$1" | LC_ALL=C sort
 }
 
 tf_enum_subtests() {