Merged w/ SPICE sim

The main differences are:

*ApparatusSpiceTargetChamber [Updated geometry]
*DetectionSystemS3 [New]
*DetectionSystemSpice [Updated]
*DetectorConstruction [To build/place the S3/SiLi]
*PrimaryGeneratorAction [A couple of extra functions to emit particles at desired energies, could potentially be merged with other present functions but shouldn't be clashing for now]
*SensitiveDetector [Spice uses the SensitiveDetector class]
*TabulatedMagneticField [New] & nonUniformMagneticField [New]