forum posts, comments: make timestamps into permalinks.

Make the timestamp beneath the username on forum posts into a permalink
that links to the post in full context of the thread. For comments, make
the timestamp link to the comment in full context of the post.

* Make the timestamp in forum posts link to /forum_posts/123.
* Make the timestamp in comments link to /posts/456#comment_123.
* Make /forum_posts/123 redirect to /forum_topics/456#forum_post_123.
* Make /comments/123 redirect to /posts/456#comment_123.
* Remove the "ID: ###" and "Permalink" fields from forum posts.

app/controllers/comments_controller.rb

@@ -50,7 +50,12 @@ class CommentsController < ApplicationController
 
   def show
     @comment = Comment.find(params[:id])
-    respond_with(@comment)
+
+    respond_with(@comment) do |format|
+      format.html do
+        redirect_to post_path(@comment.post, anchor: "comment_#{@comment.id}")
+      end
+    end
   end
 
   def destroy