Merge branch 'jx/i18n-1.7.11'

Add i18n support for scripted Porcelains, and mark strings in
merge(-recursive), am, and rebase for i18n.

* jx/i18n-1.7.11:
  i18n: merge-recursive: mark strings for translation
  Remove dead code which contains bad gettext block
  i18n: am: mark more strings for translation
  rebase: remove obsolete and unused LONG_USAGE which breaks xgettext
  i18n: Rewrite gettext messages start with dash
  i18n: rebase: mark messages for translation
  i18n: New keywords for xgettext extraction from sh

git-submodule.sh

@@ -751,7 +751,7 @@ cmd_summary() {
 	if [ -n "$files" ]
 	then
 		test -n "$cached" &&
-		die "$(gettext -- "--cached cannot be used with --files")"
+		die "$(gettext "The --cached option cannot be used with the --files option")"
 		diff_cmd=diff-files
 		head=
 	fi