Add this script referenced (Action on demand) by Event

git-svn-id: http://root.cern.ch/svn/root/trunk@4639 27541ba8-7e3a-0410-8455-c3a389f83636

test/GetWebHistogram.C

+void GetWebHistogram()
+{
+   // example of script called from an Action on Demand when a TRef object
+   // is dereferenced. See Event.h, member fWebHistogram
+   
+   const char *URL = "http://root.cern.ch/files/pippa.root";
+   printf("GetWebHistogram from URL: %s\n",URL);
+   TFile *f= TFile::Open(URL);
+   f->cd("DM/CJ");
+   TH1 *h6 = (TH1*)gDirectory->Get("h6");
+   h6->SetDirectory(0);
+   delete f;
+   TRef::SetObject(h6);
+}