relax SVN archive

Better handling of empty data in the Sequence.GetValue() method.

The non-supplied user function args in the GUI tests are now set to the default.

This is for the _execute_uf() base method, and is essential for the free file format where the
column args must, in many cases, be set to None.

Fix for the free file format error column.

In a number of places it was being referred to as 'err_col' rather than 'error_col'. This is due to
legacy GUI code.

Updates to the N-state model specific code.

The default_value() and return_data_desc() methods are now defined, and the data_names() method
returns a few parameter names.

Fix for the gui.string_conv.gui_to_py() function - Syntax or other errors are now handled.

This is an issue for the value.set user functions where the text '15N' causes a SyntaxError to be
raised by the eval() call.

Fixed the N-state model description so that it is no longer about domain motions.

This stands out in the GUI when creating data pipes!

Fix for the Sequence.GetValue() method for empty selections.

The Sequence.GetValue() method now properly handles the Combo_list and single values.

The Combo_list.GetValue() method now returns a proper list of values rather than the string repr.

The Value GUI input element UpdateChoices() method now restores the current selection.

This matches the Combo_list GUI element changes.