Separate placement calls in the VolumeManager and distinguish between DetElement placements and Volume placements (currently unused)

if the hit is produced by a particle that is not kept in the MCParticle history we set the bit
added originalG4ID to Geant4Particle class for faster lookup, as this ID is stored with the hit
Otherwise we need a complicated and time-consuming logic to parse the equivalent map if this hit really belonged to that track

Add test to dump hits from MultiSegment-MultiCollections example. Investigate issue: https://github.com/AIDASoft/DD4hep/issues/141 for details

Add test to dump hits from MultiSegment-MultiCollections example. Investigate issue: https://github.com/AIDASoft/DD4hep/issues/141 for details

UserParticleHandler: fix logic for long lived particles with pre-assigned decays that end in the calorimeter

fixes an issue where the MonteCarlo history becomes inconsistent with the history from the generator because the original particle entry is not updated

- change Geant4PrimaryInteraction::VertexMap to
  std::map<int,std::vector<Vertex*>>