Input date format is now a config parameter instead of the current locale

app/Templates/config_application.php

@@ -16,6 +16,10 @@
     <?= Helper\form_label(t('Timezone'), 'application_timezone') ?>
     <?= Helper\form_select('application_timezone', $timezones, $values, $errors) ?><br/>
 
+    <?= Helper\form_label(t('Date format'), 'application_date_format') ?>
+    <?= Helper\form_select('application_date_format', $date_formats, $values, $errors) ?><br/>
+    <p class="form-help"><?= t('ISO format is always accepted, example: "%s" and "%s"', date('Y-m-d'), date('Y_m_d')) ?></p>
+
     <div class="form-actions">
         <input type="submit" value="<?= t('Save') ?>" class="btn btn-blue"/>
     </div>