relax SVN archive

Added another spin to try to catch a program bug (unsuccessfully).

Added a check for empty PDB files in the internal structural object.

Added a check to the atom_loop() to make sure structural data is loaded.

Fixes for the peak list system tests, using the new spectrum.read_intensities() user function.

Destroyed assign_func() and shifted all the data storage back to generic_fns.spectrum.read().

The peak list type is now automatically determined.

The new autodetect_format() function was written, and the top half of the read() function was
modified to handle the auto-detection.

Fixed the args and docstring for the generic_fns.spectrum.read() function.

Updated the relax_fit.py sample script to match the changes of r7954 to the system test script.

The script now uses the new spectrum user function class.

Expanded the relax_fit.py system test script to include the creation of a number of files.

These include files of Rx values, the results file, grace files, and the saved state file.

Updated the relax_fit.py system test script for the new spectrum user function class.