Method get_column_aggregate_function

* given a column name, try to guess the aggregate function name. For now this * expects columns with a format like * colname_cnt * colname_max * colname_avg * * It checks the last letters after an underscore and returns an aggregate function that most * closely matches. Supported types are: * _sum _cnt = SUM * _avg, _median = AVG * _min, _95,

($name)