add TranslateString() utility function

core/core.go

@@ -121,3 +121,11 @@ func (d *FullData) WriteJSON(dataPath string) error {
 	err = os.Rename(path, filepath.Join(dataPath, "comitium.json"))
 	return err
 }
+
+// TranslateString takes a template string, a localizer tag, and a localizer
+// replacement set and will get the localized string from the localizer tag,
+// replace everything using the localizer replacements, and then substitute that
+// string into the template string.
+func TranslateString(template, localizerTag string, replacements *localizations.Replacements) string {
+	return fmt.Sprintf(template, Localizer.Get(localizerTag, replacements))
+}