remove commented, and useless lines

Add DD4HEP prefix so the macro is not picked up by other packages using the original macro, which they should take from ilcutil

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

 - make clear that  void fieldComponents() has to add
   the new field to the given field vector