Implemented initial systemtest Relax_disp.test_estimate_r2eff for setting up the new user function to estimate R2eff and errors by scipy.
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 2014-08-24
Parent: [r25230]
Child: [r25232]
