relax SVN archive

Renamed the relaxation dispersion test suite data directory to 'dispersion'.

Created an icon set for relaxation dispersion.

Fix for the relax_disp.cluster user function.

The 'free spins' category is now not deleted when empty.

Added a warning for the spectrum.read user function if a peak intensity of zero is encountered.

This value can cause singular matrix failures in certain optimisation.

Expanded the write_results() method of the relaxation dispersion auto-analysis.

More Grace graphs are now being produced, and the Rex file creation is now model dependent.

Speed up of the Relax_disp.test_exp_fit system test by cutting the grid size down to 3 increments.

Fixes for the spin clustering for relaxation dispersion.

Both optimisation and Monte Carlo simulations were affected by these bugs.

Clustering is now enabled for relaxation dispersion.

The model_loop() analysis specific API method now loops over the spin clusterings, allowing a cluster
of spins to be optimised simultaneously to one set of model parameters.

Implemented the relax_disp.cluster user function.

This is for clustering spins together for a dispersion analysis.

Fix for the spin ID string for the relax_disp.cluster user function.

This is for the exp_fit.py relaxation dispersion system test script.