rigidBodyMeshMotionSolver: experimental nDoF mesh-motion solver supporting the displacement-based elliptic solvers

Specification for the tutorials/multiphase/interDyMFoam/ras/floatingObject case:

dynamicFvMesh       dynamicMotionSolverFvMesh;

motionSolverLibs   ("librigidBodyMeshMotion.so" "libfvMotionSolvers.so");

solver             rigidBodyMotionSolver;

rigidBodyMotionSolverCoeffs
{
    report          on;

    meshSolver
    {
        solver displacementLaplacian;

        displacementLaplacianCoeffs
        {
            diffusivity inverseDistance (floatingObject);
        }
    }
.
.
.