Transposed some of the 'NS R1rho 3-site' model evolution matrix elements.

These now match the 'NS R1rho 2-site' model.
Last fixes for the 'NS R1rho 3-site' dispersion models.

These now behave identically to the cpmg_fit program with the PEAK_SHIFT flag disabled.  The tilt
angle for the initial magnetisation is no longer that for the average offset but that of state A.