[gimp] app: add an extracted comment for translators on the quit dialog's text.

[Jehan Pagès <jehanp src gnome org>]

commit 9e9955480b09641f100a8abddff1c359d9ec5df2
Author: Jehan <jehan girinstud io>
Date:   Sun Oct 2 00:11:51 2016 +0200

    app: add an extracted comment for translators on the quit dialog's text.
    
    "There is one image" should not necessarily be translated to '1' in
    other languages. It depends if their singular applies only to 1, like
    in English. For instance in French, it can also apply to 0, so I fixed
    the French translation.

 app/dialogs/quit-dialog.c |    3 +++
 po/fr.po                  |    2 +-
 2 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/app/dialogs/quit-dialog.c b/app/dialogs/quit-dialog.c
index d5ed14a..42db6f6 100644
--- a/app/dialogs/quit-dialog.c
+++ b/app/dialogs/quit-dialog.c
@@ -336,6 +336,9 @@ quit_close_all_dialog_container_changed (GimpContainer  *images,
                                             dialog->accel_mods);
 
   gimp_message_box_set_primary_text (dialog->box,
+                                     /* TRANSLATORS: unless your language
+                                        msgstr[0] applies to 1 only (as
+                                        in English), replace "one" with %d. */
                                      ngettext ("There is one image with "
                                                "unsaved changes:",
                                                "There are %d images with "
diff --git a/po/fr.po b/po/fr.po
index 848400c..1671091 100644
--- a/po/fr.po
+++ b/po/fr.po
@@ -13009,7 +13009,7 @@ msgstr "Si vous fermez ces images maintenant, les changements seront perdus"
 #, c-format
 msgid "There is one image with unsaved changes:"
 msgid_plural "There are %d images with unsaved changes:"
-msgstr[0] "Il y a une image avec des modifications non enregistrées :"
+msgstr[0] "Il y a %d image avec des modifications non enregistrées :"
 msgstr[1] "Il y a %d images avec des modifications non enregistrées :"
 
 #: ../app/dialogs/quit-dialog.c:311