cleanup: more unused classes/files
The following files (respective the classes defined in) are not used in OPAL:
Particle/ParticleInteractLayout.h
Particle/ParticleInteractLayout.h
Particle/ParticleCashedLayout.h
Particle/ParticleCashedLayout.hpp
Particle/NoParticleCachingPolicy.h
Particle/Cellparticlecachingpolicy.hCan they be removed?