message: Adding collision geometry for embedded cocktail
diff: #include "AliRun.h"
  #include "AliLog.h"
  #include "AliMC.h"
  +#include "AliHeader.h"
  +#include "AliVertexGenFile.h"
  #include "AliGenCocktailEventHeader.h"
  +#include "AliGenHijingEventHeader.h"
  +#include "AliGenDPMjetEventHeader.h"
  ClassImp(AliGenCocktail)
  @@ -221,11 +225,27 @@ void AliGenCocktail::Generate()
  //
  if (entry->Formula() != 0)
  {
  + AliCollisionGeometry* coll = NULL;
  +
  if (!collentry) {
  + const AliVertexGenFile* vtxGen = (AliVertexGenFile*)gAlice->GetMCApp()->Generator()->GetVertexGenerator();
  + if(vtxGen){
  + const AliHeader* hBg = vtxGen->GetHeader();
  + if(hBg){
  + AliGenEventHeader* genHeader = hBg->GenEventHeader();
  + coll = (AliCollisionGeometry*)genHeader;
  + }
  + }
  + }
  + else{
  + coll = (collentry->Generator())->CollisionGeometry();
  + }
  +
  + if (!coll) {
  Fatal("Generate()", "No Collision Geometry Provided");
  return;
  }
  - AliCollisionGeometry* coll = (collentry->Generator())->CollisionGeometry();
  +
  Float_t b = coll->ImpactParameter();
  Int_t nsig = Int_t(entry->Formula()->Eval(b));
  Int_t bin = entry->Bin() - 100;
  