gains option to return grouped results for the match success rate, based on the by_group parameter
removes calculation of match success rate of the aggregate loan book by default. This is now covered by setting by_group = NULL in config.yml
gains some additional logic to ensure that reading in the raw loan books does not fail when by_group == "group_id". Contrary to other by_group variables, "group_id" is not set by the user and can therefore not be selected when reading the raw files
by_groupparameterby_group = NULLinconfig.ymlby_group == "group_id". Contrary to otherby_groupvariables,"group_id"is not set by the user and can therefore not be selected when reading the raw files