Added gui test Relax_disp.test_r2eff_err_estimate, to test the setting of MC Sim to -1 for exponential R2eff error estimation.
task #7822(https://gna.org/task/index.php?7822): Implement user function to estimate R2eff and associated errors for exponential curve fitting.
Authored by: tlinnet 2014-08-27
Parent: [r25359]
Child: [r25361]
