grainInteraction → Particles Relation

File in src/Interaction/grainInteraction	Includes file in src/Particles
boundaries / boundaryGrainInteraction / boundaryGrainInteraction.hpp	GrainParticles / grainParticles / grainParticles.hpp
grainInteraction / grainInteraction.hpp	GrainParticles / grainParticles / grainParticles.hpp