relax SVN archive

This release includes both added features and bug fixes. The Euler angle beta of the diffusion
tensor is now treated as a glide reflection when between pi and 2pi rather than a translation of the
space between 0 and pi. The glide reflection and translation symmetries of the spheroid and
ellipsoid diffusion tensors are now collapsed such that all angles are between 0 and pi, and the
simulated values lie pi/2 either side of the fitted value.