relax SVN archive

Removed the Python 3 byte array hack which should have been removed earlier.

This code is from r17669 which should have been removed at r17712 but was accidentally left out.
Instead of reverting, the code has been deleted as r17669 contained another useful change.

The OMP model-free results file generation script now outputs for any relax version.

Python 3 fix for the Mf.test_latex_table system test.

The latex_mf_table.py model-free system test script docstring contains backslashes, so the raw
string format r"""Text""" is now used.

Small comment edit.

Python 3 support for Modelfree4 and Dasha.

The subprocess.Popen class works with byte arrays rather than strings in Python 3+. The Python
objects are now interconverted when the Python 3 encode() and decode() methods are detected.

Removed the pickle format information and arguments from the state user function definitions.

Eliminated the State.test_state_pickle() system test as pickled states are no longer supported.

Removed the ability to save and restore states using the pickle module.

A pickled state is of no use to relax anymore. It's removal is needed for Python 3 support. So now
everything defaults to the XML formatted output.

Python 3 fix - removed the use of the string module from generic_fns.spectrum.

Fix for the Relax_fit.test_bug_12670_12679() system test for the changes to Grace files at r17716.