Edit Reason cannot be empty

Requested by TheMarauder in this topic, this snippet forces users to enter an edit reason when editing their post. Their post will not be submitted until there is at least 1 character in the edit reason box.

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posting.php
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             $error[] = sprintf($user->lang['IP_BLACKLISTED'], $user->ip, $dnsbl[1]);
          }
       } 

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        if (empty($post_data['post_edit_reason']) && $mode == 'edit' && $auth->acl_get('m_edit', $forum_id) && ($user->data['user_id'] != $post_data['poster_id']))
       {
          $error[] = $user->lang['EDIT_REASON_EMPTY'];       
       } 

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language/en/posting.php
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       'EDIT_REASON'            => 'Reason for editing this post',

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Feel free to change the following text to your liking

       'EDIT_REASON_EMPTY'       => 'You are required to enter an edit reason before submitting',

Right now users will have to click the "back" button in their browser so they return to the edit screen. I'm not sure if a link to the posting/edit screen would work as it may wipe out any edits the user has made. Credit goes to RMcGirr83 for updates made to this snippet.