improve gantt performace : don't add task/milestone block if its start date is later than gantt's end date
improve gantt performace : don't add task/milestone block if its start date is later than gantt's end date

xuewenfei/jobsworth,rafaspinola/jobsworth,digitalnatives/jobsworth,ari/jobsworth,xuewenfei/jobsworth,webstream-io/jobsworth,webstream-io/jobsworth,rafaspinola/jobsworth,webstream-io/jobsworth,webstream-io/jobsworth,digitalnatives/jobsworth,digitalnatives/jobsworth,ari/jobsworth,rafaspinola/jobsworth,ari/jobsworth,xuewenfei/jobsworth,xuewenfei/jobsworth,digitalnatives/jobsworth,digitalnatives/jobsworth,ari/jobsworth,rafaspinola/jobsworth