e.g. the motion of two counter-rotating AMI regions could be defined:

dynamicFvMesh   dynamicMotionSolverListFvMesh;

solvers
(
    rotor1
    {
        solver solidBody;

        cellZone        rotor1;

        solidBodyMotionFunction  rotatingMotion;
        rotatingMotionCoeffs
        {
            origin        (0 0 0);
            axis          (0 0 1);
            omega         6.2832; // rad/s
        }
    }

    rotor2
    {
        solver solidBody;

        cellZone        rotor2;

        solidBodyMotionFunction  rotatingMotion;
        rotatingMotionCoeffs
        {
            origin        (0 0 0);
            axis          (0 0 1);
            omega         -6.2832; // rad/s
        }
    }
);

Any combination of motion solvers may be selected but there is no special
handling of motion interaction; the motions are applied sequentially and
potentially cumulatively.

To support this new general framework the solidBodyMotionFvMesh and
multiSolidBodyMotionFvMesh dynamicFvMeshes have been converted into the
corresponding motionSolvers solidBody and multiSolidBody and the tutorials
updated to reflect this change e.g. the motion in the mixerVesselAMI2D tutorial
is now defined thus:

dynamicFvMesh   dynamicMotionSolverFvMesh;

solver solidBody;

solidBodyCoeffs
{
    cellZone        rotor;

    solidBodyMotionFunction  rotatingMotion;
    rotatingMotionCoeffs
    {
        origin        (0 0 0);
        axis          (0 0 1);
        omega         6.2832; // rad/s
    }
}

inline Foam::vector Foam::septernion::transformPoint(const vector& v) const
{
    return r().transform(v - t());
}

Now there is a 1:1 correspondence between septernion and
spatialTransform and a septernion constructor from spatialTransform
provided.

Additionally "septernion::transform" has been renamed
"septernion::transformPoint" to clarify that it transforms coordinate
points rather than displacements or other relative vectors.

Avoids the clutter and maintenance effort associated with providing the
function signature string.

This reverts commit c5bea524.

This reverts commit b18f6cc1.