Move generator status setting to common place

  - prepend namespace CLHEP where missing

Geant4Output2LCIO: Use event and run number offset also in the case of presence of input event parameters extension

Geant4Output2LCIO: get LCIO input event parameters from dedicated event extension (if exists) and write them to LCIO output event

Added run and event number offsets to start counting runs and events from a different value than 0. Added float, int and string event parameters to class properties allowing a steering from outside

Improve the CMS example. Add word for the raw generator status of generator particles to Geant4Particle

 - add all parentless particles to outgoing vertex