relax SVN archive

Python 3 preparation - removed all xrange() calls from the unit tests, these are not needed.

Last Python 3 compatibility update for the system tests - they are now both Python 2 and 3 compatible!

The command used was:
2to3 -w \
-f except \
-f import \
-f imports \
-f long \
-f numliterals \
-f xrange \
.

Python 3 preparation - the test_suite.system_tests package now uses the absolute module path for imports.

Python 3 preparation - changed the import of SystemTestCase to use the absolute module path.

Removed all of the xrange() calls from the system tests as these are not necessary.

This is in preparation for Python 3.

Fix for a fatal bug introduced in the last revision (r17576).

Some changes in preparation for Python 3.

Fix for bug #20201 (https://gna.org/bugs/?20201).

The bruker.read user function can now handle the situation where multiple spins per residue are
already loaded prior to the user function call. The isotope value from the DC file is now
translated to the element name and this is used as part of the spin ID string.

Removed the 'force flag' text from the RelaxWarning messages output by the bruker.read user function.

The force flag arguments of the generic_fns.mol_res_spin.name_spin() and
generic_fns.mol_res_spin.set_spin_isotope() functions can now be set to None to suppress the text.

Fixes for the checks in the Mf.test_mf_auto_analysis() GUI test for the recent test suite data changes.