relax SVN archive

Fix for the Mf.test_bug_24131_missing_interaction system test.

This is part of bug #24131 (https://gna.org/bugs/?24131), the BMRB export failure with the
SpinContainer object having no s2 value. The problem was when assembling the diffusion tensor data.
The spin_loop() function was being called, as the diffusion tensor is reported for all residues.
Therefore the skip_desel=True has been added to match the model-free part.

Added the Mf.test_bug_24131_missing_interaction system test to catch another problem.

This is part of bug #24131 (https://gna.org/bugs/?24131), the BMRB export failure with the
SpinContainer object having no s2 value. However the previous fix of skipping deselected spins
introduced a new problem of relax still searching for the interatomic interactions for that
deselected spin.

Another fix for bug #24131 (https://gna.org/bugs/?24131).

This is the BMRB export failure when the SpinContainer object has no s2 attribute. Now no data is
stored in the BMRB file if a model-free model has not been set up for the spin. This allows the
test suite to pass.

Modified the Mf.test_bug_24131_bmrb_deposition system test to check for the RelaxError.

The test results in a RelaxError, as the results file contains no selected spins.

Modified the behaviour of the bmrb.write user function backend for a model-free analysis.

This is in the bmrb_write() method of the model-free analysis API. Deselected spins are now skipped
and a check has been added to be sure that spin data has been assembled.

Created a system test for catching bug #24131.

This is the BMRB export failure when the SpinContainer object has no s2 attribute, as reported by
Martin Ballaschk at https://gna.org/bugs/?24131.

Fix for small spin id error in tutorial script.

Adding 2 tutorial scripts.

Adding a tutorial script.

Added spaces to install script for better printing.