get_test_data: Get a yields to use in simulation
In smmueller/plotdesignr: Design Agronomic Field Experiments with more Power

Get a yields to use in simulation

1	get_test_data(config)

config

list; a named list containing all the needed inputs. The following must be included:

path string; directory where the files are stored
files string; names of files to be opened within the directory given by path.
file_ids string; names to assign to new columns. Must be in the same order as files.
var_of_interest string; column name that should be retained for simulation experiments. Should be either length 1, if the needed name is the in all files, or length(files).