Adds subtasking (#443) including:

* priority, start/due dates, progress, estimate, spent time roll-up to parent issues
* descendant issues tree displayed on the issue view with context menu support
* issue tree display on the gantt chart
* issue tree copy on project copy
* unlimited nesting

Defining subtasks requires the new permission 'Manage subtasks'.
Subtasks can not belong to a different project than the parent task.

Implementation is based on scoped nested sets for fast reads and updates.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@3573 e93f8b46-1217-0410-a6f0-8f06a7374b81

vendor/plugins/acts_as_customizable/lib/acts_as_customizable.rb

@@ -77,6 +77,13 @@ module Redmine
           @custom_field_values = nil
         end
         
+        def reset_custom_values!
+          @custom_field_values = nil
+          @custom_field_values_changed = true
+          values = custom_values.inject({}) {|h,v| h[v.custom_field_id] = v.value; h}
+          custom_values.each {|cv| cv.destroy unless custom_field_values.include?(cv)}
+        end
+        
         module ClassMethods
         end
       end

vendor/plugins/awesome_nested_set/lib/awesome_nested_set.rb

@@ -256,7 +256,7 @@ module CollectiveIdea #:nodoc:
         end
         
         def leaf?
-          right - left == 1
+          new_record? || (right - left == 1)
         end
 
         # Returns true is this is a child node