I added the option for residuals to be added to the prediction of the original points.

[inakineitor]

If in any regression function options.residuals === true, the returned points will have the following structure.

[{
coordinates: [x, y],
residual: e // Residual = Actual - Predicted
}, ...]

[inakineitor]

The code missed the target amount of line by 9 lines. Should I refactor and move functions to separate files?