formats a var-stat-strata array by var, with rounding potentially rounding a bit less for an "adj.diff" column
original_units_var_formatter(arr, digits, var_format = list())
array of same dimension as arr but of type character
numeric array
number of digits for rounding
A list of lists. Each named item of the outer list will be matched to a variable. The inner lists should have two items, `mean` and `diff`. The first formats statistics based on averages. The `diff` item should format statistics that are differences.
Hansen