Added SmartField class

- Sums electrodes only on access (at a point)
Simplified/Generalised Particle class and added derived class,
AntiHydrogen
Started on ParticleGenerator

- Rewrote myDist.h to become IntegerDistribution.h and use CRTP

- Various fixes elsewhere
Finished ParticleGenerator

- yes
Wrote Doxygen documentation for everything I could

- Also split IntegerDistribution into .h and .cpp and got rid of the
CRTP because I realised that static polymorphism was precisely the
opposite of what I wanted

- That'll teach me to be seduced by an acronym
Started worked on VoltageScheme

- Moved non-CPP files to Non-FlyE directory

- Started on VoltageScheme and derived classes. See TODOs in here.