Custom Simulations with Geant4 10.7
This MR consists of all the necessary changes to run fast simulations in Gaussino with Geant4 10.7. It is a combination of multiple MRs:
- !20 (merged) Fast Simulation Interface
- !52 (merged) Extensions of MCCollector
- !44 (merged) Example/Tutorial Shower Model
Right now we test the FASTSIM branch separately in lhcb-gaussino-fastsim, but will add lhcb-gaussino once we are in the state in master to use Geant 10.7