Add a user link to the heading of the diary comments page

Fixes #3369

This makes the heading match the layout of the user's Notes page,
which also has a short heading and a subheading with a link.

Additionally, add a page title, again for consistency

app/controllers/diary_entries_controller.rb

@@ -235,6 +235,8 @@ class DiaryEntriesController < ApplicationController
   end
 
   def comments
+    @title = t ".title", :user => @user.display_name
+
     conditions = { :user_id => @user }
 
     conditions[:visible] = true unless can? :unhidecomment, DiaryEntry