Rework wiki page versions index/diff views

- Changed to using the diff-body CSS class
-- Removed unnecessary elements from the CSS style file
- Does a symmetric difference on the array fields to detect differences
- Add more descriptors to the status/changes column
- Specifically add <br> to statuses to cause line breaks

app/views/wiki_page_versions/diff.html.erb

@@ -10,7 +10,7 @@
 
   <%= wiki_other_names_diff(@thispage, @otherpage) %>
 
-  <div>
-    <%= wiki_body_diff(@thispage, @otherpage) %>
+  <div class="diff-body">
+    <%= diff_body_html(@thispage, @otherpage, :body) %>
   </div>
 <% end %>