Changes

* Created the test_ns_cpmg_2site_expanded_no_rex8() relaxation dispersion unit test. This is a demonstration, showing the [[NS CPMG 2-site expanded]] model with no exchange when k_ex = 1e⁵. I.e. when the motion is too fast for exchange to be observed. This test should be used for all dispersion models to make sure that they model this edge case correctly as well. This follows from http://article.gmane.org/gmane.science.nmr.relax.devel/5906.

* Attempt at fixing [https://gna.org/bugs/?22071 bug #22071, the relax unit test and system test not functioning]. The fix here is that the git commands to show the current subversion revision number only works when run from the relax base directory, or one of the subdirectories. This should now be fixed, as the pipe running the command will first 'cd' to the relax base directory.

* Changed most default dispersion parameter values to avoid edge cases where there is no exchange. The Δω parameters were all 0.0 and k_ex 1e⁵, both of which result in no exchange. If this is ever used for an optimisation starting point - which it never should, apart from development, test suite, and debugging purposes - then the optimisation algorithm will have a very hard time recovering. The p_A parameter has been changed to 0.90 to set it to a reasonable value while still staying far away from the no exchange condition of p_A = 1.0. This follows from http://article.gmane.org/gmane.science.nmr.relax.devel/5917.

* Fixes for 3 dispersion system tests for the change in default parameter values. The default values are used in the auto-analysis in the test suite to avoid the grid search. The changed values affected the optimisation of two spins from Flemming Hansen's data located at test_suite/shared_data/dispersion/Hansen/, residue 4 used as an example of no exchange and residue 70 used as an example where data is only available at one field. The system test Relax_disp.test_set_grid_r20_from_min_r2eff_cpmg was also modified as it was directly checking these default values.