message: Remove AliStack from CODEX creation
diff: #include "AliPIDResponse.h"
  #include "AliMCEventHandler.h"
  #include "AliMCEvent.h"
  -#include "AliStack.h"
  #include "AliTOFPIDResponse.h"
  #include "TH2I.h"
  @@ -143,15 +142,11 @@ void AliAnalysisCODEXtask::UserExec(Option_t *){
  AliFatal("You asked for MC analysis, but I don't find any MCEventHandler... did you forget to add it to your analysis manager?");
  }
  //
  - AliMCEvent* mcEvent = 0x0;
  - AliStack* stack = 0x0;
  + AliMCEvent* mcEvent = nullptr;
  if (eventHandler) mcEvent = eventHandler->MCEvent();
  if (!mcEvent && mMCtrue)
  AliFatal("Missing MC event");
  if (mMCtrue) {
  - stack = mcEvent->Stack();
  - if (!stack)
  - AliFatal("Missing MC stack");
  mHeader.mEventMask |= kMCevent;
  }
  @@ -267,7 +262,7 @@ void AliAnalysisCODEXtask::UserExec(Option_t *){
  if (mMCtrue) {
  int label = track->GetLabel();
  - TParticle* part = stack->Particle(abs(label));
  + TParticle* part = mcEvent->Particle(abs(label));
  if (!part) continue;
  int particle_mask = GetParticleMask(part);
  if (!particle_mask) continue;
  @@ -285,8 +280,8 @@ void AliAnalysisCODEXtask::UserExec(Option_t *){
  if (TOFmismatch) t.mask |= kTOFmismatch;
  }
  - if (stack->IsPhysicalPrimary(abs(label))) t.mask |= kIsPrimary;
  - else if (stack->IsSecondaryFromMaterial(abs(label))) t.mask |= kIsSecondaryFromMaterial;
  + if (mcEvent->IsPhysicalPrimary(abs(label))) t.mask |= kIsPrimary;
  + else if (mcEvent->IsSecondaryFromMaterial(abs(label))) t.mask |= kIsSecondaryFromMaterial;
  }
  /// If everything went OK pushing the track
  @@ -303,8 +298,8 @@ void AliAnalysisCODEXtask::UserExec(Option_t *){
  t.DCAz = 0;
  t.TPCchi2NDF = 0;
  t.ITSchi2NDF = 0;
  - for (int iP = 0; iP < stack->GetNtrack(); ++iP) {
  - TParticle* particle = stack->Particle(iP);
  + for (int iP = 0; iP < mcEvent->GetNumberOfTracks(); ++iP) {
  + TParticle* particle = mcEvent->Particle(iP);
  if (!particle)
  continue;
  @@ -316,8 +311,8 @@ void AliAnalysisCODEXtask::UserExec(Option_t *){
  if (!particle_mask)
  continue;
  t.mask = particle_mask;
  - if (stack->IsPhysicalPrimary(iP)) t.mask |= kIsPrimary;
  - else if (stack->IsSecondaryFromMaterial(iP)) t.mask |= kIsSecondaryFromMaterial;
  + if (mcEvent->IsPhysicalPrimary(iP)) t.mask |= kIsPrimary;
  + else if (mcEvent->IsSecondaryFromMaterial(iP)) t.mask |= kIsSecondaryFromMaterial;
  t.eta = particle->Eta();
  t.phi = particle->Phi();
  