Geant4 support in SSD

[fhagemann]

Things that are still needed for full Geant4 support in SSD:

Geometry parsing and GDML file creation

• [x] Geometry handling of Torus and RegularPrism (#388)
• [x] Correct handling of composite rotations (#388)
• [x] Definition of all compound materials defined in MaterialProperties.jl in the Geant4 materials.xml (#392)

Running Geant4 simulations

• [x] Implement some functions to place a radioactive source and to generate Geant4 events
  • [x] Collimated, directed source (#390)
  • [x] Isotropic source emission (#390)
  • [x] Monoenergetic source (pass energy) (#393)
  • [x] Actual isotope (with isotope decay chains) (#393)
• [x] IO for Geant4 simulation output in an SSD compatible format (DetectorHitEvents): see exact format here: https://github.com/JuliaPhysics/SolidStateDetectors.jl/blob/main/src/Units.jl#L102-L113
• [x] Check that the clustering algorithms in src/ChargeClustering perform well
• [x] Implement and test functions to generate and save pulse shapes from Geant4 output, maybe even without the need to save the intermediate DetectorHitEvents if not needed (#395)

Documentation

• [x] Documentation on how to use the Geant4 extensions
• [x] Docstrings for exported/extended functions (#409)
• [x] Tutorial for the documentation (small code example on how to use Geant4 and SSD) (#398)

Plot recipes

• [x] Add plot recipe for radioactive source (#396) Optional: add plot recipe for events (in RadiationDetectorSignals?)

Testing

• [x] Add tests for the new Geant4 functionality and GDML parsing (#401)

[hervasa2]

Here is a list of the additions we discussed and a couple other ones that occurred to me.

• [x] Output the total number of primaries simulated. This is needed for efficiency calculations (#403)
• [x] Directed cone emission (#400)
• [x] Progress bar for run_geant4_simulation (#399)