relax SVN archive

The branch existed from r2178 to r2199 and was merged with the command:

$ svn merge file:///data1/src/repositories/relax/1.0@... file:///data1/src/repositories/relax/branches/diff_tensor@...

All references to isotropic, axially symmetric, and fully anisotropic diffusion have been changed to
sphere, spheroid, and ellipsoid. The geometric parameters of the Brownian diffusion tensor are now
defined as

Diso = 1/3 (Dx + Dy + Dz),
Da = Dz - 1/2(Dx + Dy),
Dr = Dy - Dx / 2Da,

and the weight and correlation time functions for calculating the value, gradient, and Hessian have
been updated to match these equations. Many old bugs in the ellipsoid and spheroid Hessians have
been removed.