Add a button for end users to purge cache if they want to.

Edit lib/tpl/default/main.php.

lib/tpl/default/main.php

    <div class="bar-left" id="bar__topleft">
      <?php tpl_button('edit')?>
      <?php tpl_button('history')?>
      <?php print html_btn('purgecache', $ID, '', array('purge' => 'true')) ?>
    </div>