Take a sequence of vector, matrix or data-frame arguments and combine by
rows. Contrary to rbind it handles non-matching column
names.
There is also special method for the results of
cro/cro_fun/tables/fre.
action if there are non-matching columns between
data.frames. Possible values are "add", "drop", "stop".
"add" will combine all columns, "drop" will leave only common
columns, "stop" will raise an error.