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*>>

Use in event readers like:
MyReader::setParameters( std::map< std::string, std::string > & parameters ) {
  // int (or double, ...) m_parameter, defaultValue
    _getParameterValue( parameters, "MyParameters", m_parameter, defaultValue);
 }

TrackerWeightedAction: Fix defaults which caused an empty hit to be stored which broke the MCHistory

Fix example DDG4/examples/readHEPMC.py and allow access to STL containers from DD4hep python interface

 - changed signature of Geant4EventReader::readParticles(int,Vertex*, Particles&)
   to Geant4EventReader::readParticles(int,Vertices&, Particles& )
 - implement in LCIOEventReader, Geant4EventReaderHepEvt and Geant4EventReaderHepMC
 - for now still one vertex only is created using the first final state particle
   for HepEvt and LCIO

Add possibility to remove the production cut from region so that it uses the Global Range Cut instead of the default set for Regions

Geant4 will print a warning about regions without thresholds, but that is what we need. This allows one to keep regions for e.g., creating material scan with out manually having to set range cuts
As far as I can tell the threshold is only used when store_secondaries is true (which is ignored), so we are now throwing an exception if someone specifies store_secondaries without setting a threshold.
However, it seems that store_secondaries is actually never used anywhere else?

TSystem::Load return > 0 if the library is already loaded. This is not an error. For some reason it was already loaded when I run ddsim in a singularity container. I have no idea why.