Inserted systemtest Relax_disp.test_finite_value, to illustrate the return of inf from C-code exponential, when R is negative.
This can be an issue, if minfx takes a wrong step when no constraints are implemented.
bug #22552(https://gna.org/bugs/index.php?22552): Chi2 value returned from C-code Curve-fitting return 0.0 for wrong parameters -> Expected influence on Monte-Carlo sim.
