Linear Quantile Mixed Model (lqmm)

[mkrasmus]

I think a useful addition would be the Linear Quantile Mixed Model. As with quantile regression, it has become a fairly popular go to modelling approach especially in psychology / education. I think some of the functionality of the lqmm package is imported from nlme (eg ranef). The only additional parameter would require the user to set the tau. I haven't seen this feature raised in currently opened issues or past closed issues.