relax SVN archive

Updated all of the sample scripts for the new relaxation data ID string design.

Added copyright headers to all of the sample scripts, and updated the introduction text.

This allows users to determine the age of the scripts.

Updated the CV model-free model selection script to the new relax data ID string design.

Shifted all of the model-free sample scripts into the new subdirectory sample_scripts/model_free.

Created the test_back_calc_new() relaxation data system test for the back calculation of new data.

Renamed test_back_calc2() to test_back_calc_specific().

Added the test_back_calc2() relaxation data system test for back calculation of specific data.

Added some data checks to the test_back_calc() system test of the relax_data.back_calc() user fn.

The ri_data_bc structure is not initialised by the model-free data_init() method.

The ri_data_bc data structure is now returned by get_data_name().