This function returnes residuals in x-direction (x-xhat),
in y-direction(y-yhat) and optimized residuals. The
optimized residuals correspond to distances between data
points and the regression line which were optimized for
regression coefficients estimation. In case of
Passing-Bablok Regression orthogonal residuals will be
returned as optimized residuals . The residuals in
x-direction are interesting for regression types which
assume errors in both variables (deming, weighted deming,
Passing-Bablok), particularily for checking of model
assumptions.