relax SVN archive

Modified the grid search upper bounds functions for the relaxation curve-fitting.

This is for both the exponential relaxation curve-fitting analysis and the same fitting in the
dispersion analysis. The intensity values are doubled and then rounded to the next order. This
ensures that I0 and Iinf will be within the grid bounds. Hence the zooming grid search can be used
for these curves.

Completed the Relax_fit.test_zooming_grid_search system test.

Now only a single spin is optimised. The zooming levels increase in integer increments from 0 to 50
so that the final zoomed grid is insanely small (as the curve-fitting C modules are incredibly fast,
this test is nevertheless relatively quick). The final zooming grid search parameter values are
checked to see if they are the same as those optimised in the Relax_fit.test_curve_fitting_height
system test to demonstrate the success of the algorithm.

Expanded the minimise.grid_zoom user function documentation.

A few sentences about the limitations of the algorithm have been added.

Large expansion of the minimise.grid_search user function documentation.

The previous documentation was essentially non-existent.

Alphabetical ordering of the minimisation user functions in the user_functions.minimisation module.

Changed the minimise.grid_zoom user function.

The zoom level can now be any floating point number or integer, including negative values. The user
function docstring has been significantly expanded to explain the entire zooming grid search
concept.

Removed a debugging printout.

Modified the zooming grid search algorithm.

If the zoom level is negative, hence the grid will be larger than the original, the checks that the
grid is within the original are no longer active.

Implemented the zooming grid search.

If the zoom level is set to any value other than 0, then the grid width will be divided by
2**zoom_level and centred at the current parameter values. If the new grid is outside of the bounds
of the original grid, the entire grid will be translated so that it lies entirely within the
original.

The rx parameter of the relaxation curve-fitting analysis now has 'rad.s^-1' units defined.