Performance improvement on calendar and gantt (about 45% on gantt for large number of issues).

Partial issues/_tooltip is replaced by an helper and some translated strings are now cached.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@794 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/helpers/issues_helper.rb

@@ -17,6 +17,19 @@
 
 module IssuesHelper
 
+  def render_issue_tooltip(issue)
+    @cached_label_start_date ||= l(:field_start_date)
+    @cached_label_due_date ||= l(:field_due_date)
+    @cached_label_assigned_to ||= l(:field_assigned_to)
+    @cached_label_priority ||= l(:field_priority)
+    
+    link_to_issue(issue) + ": #{h(issue.subject)}<br /><br />" +
+      "<strong>#{@cached_label_start_date}</strong>: #{format_date(issue.start_date)}<br />" +
+      "<strong>#{@cached_label_due_date}</strong>: #{format_date(issue.due_date)}<br />" +
+      "<strong>#{@cached_label_assigned_to}</strong>: #{issue.assigned_to}<br />" +
+      "<strong>#{@cached_label_priority}</strong>: #{issue.priority.name}"
+  end
+
   def show_detail(detail, no_html=false)
     case detail.property
     when 'attr'