This function was written by Kelly Karl in January 2022
This function calculates the area under the curves, the error, and the
value for kappa and its error based on the paper “Quantitative Assessment of Ligand Bias from Bias Plots: The Bias Coefficient Kappa” by Karl and Hristova.
To use enter the fit parameters in the following manner ([Etopligx, KAligx,
nligx, Etopligy, KAligy, nligy, Etoprefx, KArefx, nrefx, Etoprefy, KArefy,
nrefy](errors in the same order)]