relax SVN archive

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.

Python 3 fix for the relax_io.open_write_file() function.

This now matches the behaviour of open_read_file() in that there are three different behaviours for
opening bz2 and gz files for writing to for the different Python versions (one for Python 2, one for
Python 3.0 to 3.2, and one for Python 3.3+). All byte streams have been eliminated as
open_write_file() is for creating text files.

Python 3 fix for the Noe.test_noe_analysis() system test for the grace.write precision changes.