post tooltips: use underscores instead of spaces in pool names.

Don't use pretty names (spaces instead of underscores) for pools in post
tooltips. This is for consistency with tags (which have underscores
here) and for easier copy & pasting.

app/views/posts/show.html+tooltip.erb

@@ -48,7 +48,7 @@
     <div class="post-tooltip-pools">
       <% @post.pools.series.undeleted.each do |pool| %>
         <%= link_to pool, class: "pool-category-#{pool.category}" do %>
-          <%= "pool:#{pool.pretty_name} [#{pool.page_number(@post.id)}/#{pool.post_count}]" %>
+          <%= "pool:#{pool.name} [#{pool.page_number(@post.id)}/#{pool.post_count}]" %>
         <% end %>
       <% end %>
     </div>