Only bother outputting the <h4> with the header if there is a title set when...

Only bother outputting the <h4> with the header if there is a title set when viewing a block. This allows people to set no title for their block if they like.

htdocs/theme/default/templates/view/blocktypecontainerviewing.tpl

     <div class="blockinstance" id="blockinstance_{$id}">
-        <div class="blockinstance-header">
+        {if $title}<div class="blockinstance-header">
             <h4>{$title | escape}</h4>
-        </div>
+        </div>{/if}
         <div class="blockinstance-content">
             {$content}
         </div>