Request support for rlm objects

Having recently discovered jtools, I really appreciate the flexibility of your package to facilitate interpretation and reporting of regression models. I'm using robust regression in my analysis, via the rlm function from the MASS package.

Please consider adding support for rlm objects to jtools. I think it should be a quick fix, as it's just a case of changing index positions and dropping non-applicable summary statistics.

Thanks for your good work!

No file or test is named. Start by tracing jtools' existing regression-object support and compare how MASS::rlm objects expose indices and summary statistics. Done means rlm objects are supported while non-applicable statistics are omitted.

Written by the indexing model from the issue text.