Remove extra DIV added to view template

One of the changes for introducing folded tiddlers was the extra reveal
widget here, which introduces an extra DIV element, breaking some CSS
rules. To fix it, we re-use the reveal widgets generated DIV as the
tiddler body DIV

core/ui/ViewTemplate/body.tid

@@ -5,9 +5,7 @@ tags: $:/tags/ViewTemplate
 $:/state/folded/$(currentTiddler)$
 \end
 
-<div class="tc-tiddler-body">
-
-<$reveal type="nomatch" state=<<folded-state>> text="hide" retain="yes" animate="yes">
+<$reveal tag="div" class="tc-tiddler-body" type="nomatch" state=<<folded-state>> text="hide" retain="yes" animate="yes">
 
 <$list filter="[all[current]!has[plugin-type]!field:hide-body[yes]]">
 
@@ -20,5 +18,3 @@ $:/state/folded/$(currentTiddler)$
 </$list>
 
 </$reveal>
-
-</div>