calibration for quantiles

[BERENZ]

So, if we would like to add calibration for quantiles for all of the models we need the following changes:

nonprob(...,  pop_quantiles=...)

and

controlSel(quantile=...)
controlOut(quantile=...)

where pop_quantiles are list of quantiles given by the user (known) or quantile argument that works as in WeightIt.

I do not want to include quantile argument in the main function as it may suggest that we want to estimate given quantile for the target / output variable(s). Any comments are welcome.