manipulators → motionDiffusivity Relation

File in src/fvMotionSolver/motionDiffusivity/manipulators	Includes file in src/fvMotionSolver/motionDiffusivity/motionDiffusivity
exponential / exponentialDiffusivity.H	motionDiffusivity.H
quadratic / quadraticDiffusivity.H	motionDiffusivity.H