课程讨论区回复帖子的内容增加删除附件功能；

增加可以编辑自己回复内容的功能；

app/controllers/messages_controller.rb

@@ -103,7 +103,11 @@ class MessagesController < ApplicationController
 
   # Edit a message
   def edit
+    if @project
       (render_403; return false) unless @message.editable_by?(User.current)
+    else
+      (render_403; return false) unless @message.course_editable_by?(User.current)
+    end
     @message.safe_attributes = params[:message]
     if request.post? && @message.save
       attachments = Attachment.attach_files(@message, params[:attachments])
@@ -124,7 +128,11 @@ class MessagesController < ApplicationController
 
   # Delete a messages
   def destroy
+    if @project
       (render_403; return false) unless @message.destroyable_by?(User.current)
+    else
+      (render_403; return false) unless @message.course_destroyable_by?(User.current)
+    end
     r = @message.to_param
     @message.destroy
     # modify by nwb

app/models/message.rb

@@ -127,6 +127,14 @@ class Message < ActiveRecord::Base
     board.course
   end
 
+  def course_editable_by?(usr)
+    usr && usr.logged? && (usr.allowed_to?(:edit_messages, course) || (self.author == usr && usr.allowed_to?(:edit_own_messages, course)))
+  end
+
+  def course_destroyable_by?(usr)
+    usr && usr.logged? && (usr.allowed_to?(:delete_messages, course) || (self.author == usr && usr.allowed_to?(:delete_own_messages, course)))
+  end
+
   def editable_by?(usr)
     usr && usr.logged? && (usr.allowed_to?(:edit_messages, project) || (self.author == usr && usr.allowed_to?(:edit_own_messages, project)))
   end

app/views/messages/_course_show.html.erb

@@ -148,7 +148,7 @@
                               "编辑",
                               {:action => 'edit', :id => message},
                               :title => l(:button_edit)
-                      ) if message.editable_by?(User.current) %>
+                      ) if message.course_editable_by?(User.current) %>
                   <%= link_to(
                               #image_tag('delete.png'),
                               "删除",
@@ -156,7 +156,7 @@
                               :method => :post,
                               :data => {:confirm => l(:text_are_you_sure)},
                               :title => l(:button_delete)
-                      ) if message.destroyable_by?(User.current) %>
+                      ) if message.course_destroyable_by?(User.current) %>
                 </div></td>
             </tr>
             <tr>