Adds watch/unwatch functionality at forum topic level (#1912).

Users who create/reply a topic are automatically added as watchers but are now able to unwatch the topic.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@1878 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/message_observer.rb

@@ -17,8 +17,9 @@
 
 class MessageObserver < ActiveRecord::Observer
   def after_create(message)
-    # send notification to the authors of the thread
-    recipients = ([message.root] + message.root.children).collect {|m| m.author.mail if m.author && m.author.active?}
+    recipients = []
+    # send notification to the topic watchers
+    recipients += message.root.watcher_recipients
     # send notification to the board watchers
     recipients += message.board.watcher_recipients
     # send notification to project members who want to be notified