relax SVN archive

Converted spectrum.read_intensities() to use the new relax_io.read_spin_data_file() function.

This is only for the generic formatted file.

Docstring modification better explaining spin_id.

Converted value.read() to use the new relax_io.read_spin_data_file() function.

This converts the user function to the 1.3 line design as well.

Added a check to see if the file is empty to read_spin_data_file().

Fixed the calls to rdc.read() and pcs.read() in the system tests.

Fixes for the unit tests of generic_fns.mol_res_spin.generate_spin_id_data_array().

Modified generic_fns.rdc.read() to use the new relax_io.read_spin_data_file().

Modified generate_spin_id_data_array() so that column numbering starts at 1.

Created the read_spin_data_file() generator function.

This is designed to replace quite a few inconsistent functions throughout the generic function code
base. It reads a columnar formatted file with a spin per line.

Fixed the call from the prompt to the generic fns.