relax SVN archive

Expansion of the value.set user function to handle list-type data.

The value.set user function can now handle parameters which consist of lists of values. The index
argument has been added to allow the index of the list to be specified, and this is then propagated
into the specific analysis API.

Converted the N_state_model.test_5_state_xz system test to use a new way to set parameters.

Instead of using pseudo-parameters for the value.set user function such as 'p0', 'p1', etc. for the
probabilities, which are then converted into the 'probs' parameter with the index taken from the
name, instead the index is now directly given. The value.set user function will need to be modified
to handle this. The aim is to standardise the parameter list object for the N-state model analysis.

Eliminated the model-free specific analysis API data_type() method.

This functionality is now provided by the parameter list object.

Eliminated the last of the specific analysis API return_units() methods.

This functionality is now provided by the parameter list object.

Added the PCS and RDC as parameters for the frame order and N-state model analyses.

These are now defined in the respective parameter list objects. The base method add_align_data()
has been created to avoid code duplication.

Large improvement for the lib.software.grace module.

The '*_err' and '*_bc' parameter names for the parameter error and back-calculated parameters
respectively are now supported. This allows these values to be easily plotted.

Removed the frame order API return_units() method.

This method has been superseded by the parameter list object.

Fixes for the units of the ave_pos_x, ave_pos_y, and ave_pos_z frame order parameters.

Replaced the frame order API model_type() method with the base _model_type_global() method.

The two methods were identical anyway.

Replaced the frame order specific API model_loop() method.

The base method _model_loop_single_global() is used instead.