This is the last chapter for adding multiple tablerate to Magento system. Now we need to add to our admin panel, so we can edit it.
We need to add two new files (they are duplicated from the original tablerate module):
\app\code\core\Mage\Adminhtml\Model\System\Config\Backend\Shipping\Tablerate(n).php
\app\code\core\Mage\Adminhtml\Model\System\Config\Source\Shipping\Tablerate(n).php
