/comments: break out index_by_post/index_by_comment into partials.

app/views/comments/index.html.erb

@@ -0,0 +1,19 @@
+<div id="c-comments">
+  <div id="a-index">
+    <h1>Comments</h1>
+
+    <%= render "posts/partials/common/inline_blacklist" %>
+
+    <% if params[:group_by] == "comment" %>
+      <%= render "index_by_comment" %>
+    <% else %>
+      <%= render "index_by_post" %>
+    <% end %>
+  </div>
+</div>
+
+<%= render "comments/secondary_links" %>
+
+<% content_for(:page_title) do %>
+  Comments - <%= Danbooru.config.app_name %>
+<% end %>