add ability to get count for all values of a given column and use it to speed up get_answer_count
add ability to get count for all values of a given column and use it to speed up get_answer_count

breunigs/gnt-eval,breunigs/gnt-eval,breunigs/gnt-eval,breunigs/gnt-eval,breunigs/gnt-eval,breunigs/gnt-eval,breunigs/gnt-eval