Skeleton list to declare a quantile regression model in a `Model` object.
Quantile(link = "identity", scaled = FALSE, q = 0.5)
A list with two elements naming the family and link function
Name of the link function - any of `identity`, `log`, `logit`, `inverse`, or `probit`
Logical indicating whether to include a scale parameter. If FALSE then the scale parameter is one.
Scalar in [0,1] declaring the quantile of interest.