Add command to list imported modules

src/shellfu.sh.skel

             shellfu __debug "found module file: $mpath"
             shellfu _read_directive "module-version" "$mpath"
             ;;
+        ls_imported)
+            #
+            # Print list of modules already imported
+            #
+            echo "$__SHELLFU_IMPORTED" | tr : \\n
+            ;;
 
         _do_import)
             #

tests/shellfu_import/TF_RUN

     echo "try_import_var_fn"
     echo "import_var_fn_bash"
     echo "import_var_fn_bash_hint"
+    echo "ls_imported"
 }
 
 ignored() {
     # File _ignored_ is used as list of tokens to always
     # remove from the info.
     #
+    test "$name" == ls_imported && return 0
     local target="$1"
     printf "
         {
         try_import_fn) echo 'shellfu try_import mod_f'          ;;
         try_import_var) echo 'shellfu try_import mod_v'         ;;
         try_import_var_fn) echo 'shellfu try_import mod_v_f'    ;;
+        ls_imported) echo 'shellfu import mod_v_f'
+                     echo 'shellfu try_import mod_v_f_bash'
+                     echo 'shellfu import mod_v'
+                     echo 'shellfu import mod_v_f'
+                     echo 'shellfu ls_imported'                 ;;
     esac
 }
 
     #
     local name="$1"
     mktscript "$name" > "$name.sh"
+
     mkdir -p result
     chmod +x "$name.sh"
-    env -i PATH="$PATH" SHELLFU_DIR="$SHELLFU_DIR" ./"$name.sh"
+    env -i PATH="$PATH" SHELLFU_DIR="$SHELLFU_DIR" ./"$name.sh" \
+        >"result/$name.out" 2>"result/$name.err"
+    test "$name" == ls_imported && {
+        diff -u "oracle/$name.out" "result/$name.out" || return 1
+        diff -u "oracle/$name.err" "result/$name.err" || return 1
+        return 0
+    }
     comm -13 "$name.before" "$name.after" > "result/$name.new"
     # i.e. lines introduced by import ^^
     diff -u "oracle/$name.new" "result/$name.new"

tests/shellfu_import/oracle/ls_imported.err

+shellfu: cannot find module: mod_v_f_bash

tests/shellfu_import/oracle/ls_imported.out

+mod_v_f
+mod_v