Ask user what to do with child pages when deleting a parent wiki page (#3202).

3 options are available:
* move child pages as root pages
* move child pages to another parent page
* delete all descendants

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@2676 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/wiki_page.rb

@@ -22,7 +22,7 @@ class WikiPage < ActiveRecord::Base
   belongs_to :wiki
   has_one :content, :class_name => 'WikiContent', :foreign_key => 'page_id', :dependent => :destroy
   acts_as_attachable :delete_permission => :delete_wiki_pages_attachments
-  acts_as_tree :order => 'title'
+  acts_as_tree :dependent => :nullify, :order => 'title'
   
   acts_as_event :title => Proc.new {|o| "#{l(:label_wiki)}: #{o.title}"},
                 :description => :text,