auto-managed shared "Show all tasks" filter on every board + config toggle v1.5

Template/config/show.php

@@ -40,6 +40,13 @@
         </p>
     </fieldset>
 
+    <fieldset>
+        <?= $this->form->checkbox('organon_tweaks_show_all_filter', t('Add a "Show all tasks" filter to every board'), 1, isset($values['organon_tweaks_show_all_filter']) && $values['organon_tweaks_show_all_filter'] == 1) ?>
+        <p class="form-help">
+            <?= t('Keep a shared "Show all tasks" custom filter (an empty query, so open and closed tasks are shown) on every board, old and new. It appears in the board filter bookmark menu as a one-click way to clear the filter. Turning this off removes it from all boards; turning it on recreates it everywhere.') ?>
+        </p>
+    </fieldset>
+
     <div class="form-actions">
         <button type="submit" class="btn btn-blue"><?= t('Save') ?></button>
     </div>