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

app/views/issues/show.rhtml

@@ -4,7 +4,10 @@
 
 <div class="<%= @issue.css_classes %> details">
         <%= avatar(@issue.author, :size => "50") %>
-        <h3><%=h @issue.subject %></h3>
+      
+<div class="subject">      
+<%= render_issue_subject_with_tree(@issue) %>
+</div>
         <p class="author">
         <%= authoring @issue.created_on, @issue.author %>.
         <% if @issue.created_on != @issue.updated_on %>
@@ -56,6 +59,17 @@
 
 <%= call_hook(:view_issues_show_description_bottom, :issue => @issue) %>
 
+<% if !@issue.leaf? || User.current.allowed_to?(:manage_subtasks, @project) %>
+<hr />
+<div id="issue_tree">
+<div class="contextual">
+  <%= link_to(l(:button_add), {:controller => 'issues', :action => 'new', :project_id => @project, :issue => {:parent_issue_id => @issue}}) if User.current.allowed_to?(:manage_subtasks, @project) %>
+</div>
+<p><strong><%=l(:label_subtask_pural)%></strong></p>
+<%= render_descendants_tree(@issue) unless @issue.leaf? %>
+</div>
+<% end %>
+
 <% if authorize_for('issue_relations', 'new') || @issue.relations.any? %>
 <hr />
 <div id="relations">
@@ -113,4 +127,8 @@
 <% content_for :header_tags do %>
     <%= auto_discovery_link_tag(:atom, {:format => 'atom', :key => User.current.rss_key}, :title => "#{@issue.project} - #{@issue.tracker} ##{@issue.id}: #{@issue.subject}") %>
     <%= stylesheet_link_tag 'scm' %>
+    <%= javascript_include_tag 'context_menu' %>
+    <%= stylesheet_link_tag 'context_menu' %>
 <% end %>
+<div id="context-menu" style="display: none;"></div>
+<%= javascript_tag "new ContextMenu('#{url_for(:controller => 'issues', :action => 'context_menu')}')" %>