relax SVN archive

The members list is now stored in the pseudo-spin to map this to the respective spin containers.

One more fix for test_create_pseudo_spin().

Fixes for test_create_pseudo_spin() and test_create_pseudo_spin2().

The pseudo-spin name and number is now stored in the member spin containers.

This gives a mapping between from the spin to the pseudo-spin.

Modified the checks for the pseudo-spin creation unit tests.

Wrote a second unit test for the creation of a pseudo-spin.

Added some more checks for the test_create_pseudo_spin() unit test.

Changed the default value for 'int_cpmg' to avoid an impossible mathematical situation: ln(0).

A few fixes based on the unit tests problems.

Added more unit tests and tried to debug what was uncovered by these tests.

Still more work is needed for debugging...