feat: make msgfmt.py support -o flag

Make msgfmt.py support -o flag like gnu msgfmt.

This allows:

  make -C locale local_install MSGFMT="python3 ../roundup/msgfmt.py"

to compile locale files for use when running roundup_server in
development mode.

Author: rouilj

CHANGES.txt

@@ -149,7 +149,8 @@ Features:
   weekly-report,schema-dump.py, roundup-reminder, copy-user.py,
   dump_dbm_sessions_db.py, contributors.py (John Rouillard)
 - roundup/msgfile.py can now be called as 'python msgfmt.py de.po de.mo'
-  to compile a translation file if msgfmt is missing. (John Rouillard)
+  or 'python msgfmt.py -o de.mo de.po' to compile a translation file if
+  GNU msgfmt is missing. (John Rouillard)
 - save roundup-admin history between sessions. Load
   ~/.roundup_admin_rlrc file to set history-size persistently. Add
   pragma history_length to override for a session. (John Rouillard)

doc/developers.txt

@@ -129,12 +129,18 @@ which will compile the ``.po`` source files into binary
 ``.mo`` files and install them under
 ``locale/locale/<LANGUAGE_CODE>/LC_MESSAGES/roundup.mo``. For
 German this will be
-``locale/locale/de/LC_MESSAGES/roundup.mo``.  You will need
-``msgfmt`` from the the GNU gettext tools to be installed on
-your system. In a pinch you can invoke ``python roundup/msgfmt.py
-po_file mo_file`` to compile your .po file to a .mo file. It's slow
-but seems to work in basic tests. The msgfmt.py file is used by
-Roundup to compile out of date .po files.
+``locale/locale/de/LC_MESSAGES/roundup.mo``. 
+
+By default this requires ``msgfmt`` from the the GNU gettext tools
+installed on your system. If you do not have ``msgfmt`` installed, you
+can use:
+
+  make -C locale local_install MSGFMT="python3 ../roundup/msgfmt.py"
+
+Also to compile a single .po file, you can invoke ``python
+roundup/msgfmt.py po_file mo_file`` to compile your .po file to a .mo
+file. It's slow but seems to work in basic tests. The msgfmt.py file
+is used by Roundup to compile out of date .po files.
 
 Submitting Changes
 ------------------

roundup/msgfmt.py

@@ -288,9 +288,18 @@ def getAsFile(self):
     # a really dumb attempt to make this into a command
     # Usage: python msgfmy.py <input_file>.po <output_file>.mo
     import sys
-
-    mo = Msgfmt(sys.argv[1]).get()
-    with open(sys.argv[2], 'wb') as mofile:
+    input_filename = ""
+    output_filename = ""
+
+    if sys.argv[1] == "-o":
+        output_filename = sys.argv[2]
+        input_filename = sys.argv[3]
+    else:
+        input_filename = sys.argv[1]
+        output_filename = sys.argv[2]
+
+    mo = Msgfmt(input_filename).get()
+    with open(output_filename, 'wb') as mofile:
         mofile.write(mo)
         mofile.close()