fix API inconsistency in SimCalorimeterHit

[gaede]

• remove deprecated method: void addMCParticleContribution( EVENT::MCParticle *p, float en,float t,int pdg, float* stepPos=0)
  • as it does not require the stepLength that is needed for some calo digitizers
• replace float* stepPos=0 with const float* stepPos=0 in argument list of the correct addMCParticleContribution