Add comparison modes to Group By

Transformers which have Group By do the groupping in case sensitive alpahabetic mode.

Casing is not always important and time to time I'd like group by numbers where the numeric values come inconsistently with or without leading zeros or .00 at the end.

It would save some preparation and clean up transformers before and after the groupping transformers (eg. Aggregator, StatisticsCalculator) if the Group By settings would have comparison options (case sensitive, case insensitive, numeric, etc, like in testers).