FEATURE: suggested messages for messages

FEATURE: clicking envelope takes you to inbox

Suggested messages works somewhat like suggested topics.

- New show up first (in either group inbox or inbox)
- Then unread (in either group inbox or inbox)
- Finally "related" which are messages with same participants as the current pm.

lib/topic_view.rb

@@ -295,7 +295,6 @@ class TopicView
   end
 
   def suggested_topics
-    return nil if topic.private_message?
     @suggested_topics ||= TopicQuery.new(@user).list_suggested_for(topic)
   end