Adds all alternative for submission --open option

src/canvaslms/cli/submissions.nw

@@ -201,6 +201,8 @@ for submission in submission_list:
 
   if args.open == "open":
     <<open [[tmpdir/subdir]] for the user>>
+  elif args.open == "all":
+    <<open all files in [[tmpdir/subdir]] for the user>>
 
   if <<condition that [[args.open]] tells us to spawn a shell>>:
     <<spawn shell in [[tmpdir/subdir]] for the user>>
@@ -225,13 +227,16 @@ submission_parser.add_argument("-o", "--output-dir",
        "If specified, do not print to stdout.")
 @
 
-We also have the open option, that has a choice of two alternatives.
+We also have the open option, that has a choice of a few alternatives.
 <<add submission command options>>=
 submission_parser.add_argument("--open", required=False,
-  nargs="?", default=None, const="open", choices=["open"]+choices_for_shells,
+  nargs="?", default=None, const="open",
+  choices=["open", "all"]+choices_for_shells,
   help="Open the directory containing the files using "
        "the default file manager (`open`). "
        "With `open`, the pager will be used to display the output as usual. "
+       "With `all`, all files (not the directory containing them) will be "
+       "opened in the default application for the file type. "
        <<help strings for open shell options>>
        "Default: %(const)s")
 <<condition that [[args.open]] tells us to spawn a shell>>=
@@ -319,6 +324,13 @@ open files while reading the stdout output using a pager.
 subprocess.run(["open", tmpdir/subdir])
 @
 
+If we instead want to open all files contained in the directory, we can need to 
+iterate all the files and open them one by one.
+<<open all files in [[tmpdir/subdir]] for the user>>=
+for file in (tmpdir/subdir).iterdir():
+  subprocess.run(["open", file])
+@
+
 We can also spawn a shell in the directory so that the user can work with the 
 files, for instance run the Python code in the case of a Python lab submission.
 Now, we could spawn a sub-shell of the user's shell,