Added the ability to archive projects:

* Only administrators can archive/unarchive projects.
* Once archived, the project is visible on the admin project listing only. It doesn't show up anywhere else in the app. Subprojects are also archived.
* Archive/unarchive preserve everything on the project (issues, members, ...).
* A subproject can not be unarchived if its parent project is archived.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@549 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/views/projects/calendar.rhtml

@@ -23,7 +23,7 @@
       <%= check_box_tag "tracker_ids[]", tracker.id, (@selected_tracker_ids.include? tracker.id.to_s) %>
       <%= tracker.name %><br />
     <% end %>
-    <% if @project.children.any? %>
+    <% if @project.active_children.any? %>
     <p><strong><%=l(:label_subproject_plural)%></strong></p>
     <%= check_box_tag "with_subprojects", 1, params[:with_subprojects] %> <%= l(:general_text_Yes) %>
     <% end %>