Rework pool versions index/diff views

- Changed to using the diff-body CSS class
-- Removed unneeded CSS style file
- Removed trailing whitespace after the >>> link
-- It was causing artifact line-throughs to appear after the link
- Changed the diff link to only render when a text field has changed
-- Because the post changes are already shown on the index view
- Specifically add <br> to statuses to cause line breaks

app/views/pool_versions/diff.html.erb

@@ -7,7 +7,7 @@
 
     <% if @other_version.present? %>
       <p>Showing differences between <%= compact_time @pool_version.updated_at %> (<%= link_to_user @pool_version.updater %>) and <%= compact_time @other_version.updated_at %> (<%= link_to_user @other_version.updater %>)</p>
-      <div>
+      <div class="diff-body">
         <h2>Name:</h2>
         <p>
           <% if @pool_version.name != @other_version.name %>
@@ -21,11 +21,11 @@
         <h2>Posts:</h2>
         <p><%= render "pool_versions/diff", diff: @pool_version.build_diff(@other_version) %></p>
       </div>
-      <div>
+      <div class="diff-body">
         <h2>Description:</h2>
         <p>
           <% if @pool_version.description != @other_version.description %>
-            <%= pool_page_diff(@pool_version, @other_version) %>
+            <%= diff_body_html(@pool_version, @other_version, :description) %>
           <% else %>
             <i>Unchanged.</i>
           <% end %>