relax SVN archive

The relaxation curve-fitting system tests are now skipped if the module is missing or broken.

This improves the printouts from the test suite and shows a summary of skipped tests rather than a
pile of traceback messages and errors.

The messsage about skipping the GUI tests due to wxPython being missing is now more specific.

This was being shown for all runs of the test suite when it only needs to appear if GUI tests have
been run.

Added a Python 3 version of the truncated OMP model-free results file.

This was created with trunk which is during the 2.1 relax releases.

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.