As the 'average' and 'percentage' aggregation types both return
float values, we should ensure they are output with localised
formatting (e.g. decimal separator).
This option allows report creators to avoid duplicate data being
displayed in their report. It is applied only when no columns in the
report currently have aggregation methods applied.
The group concatenation types now consistently sort the returned values
and support aggregating columns containing multiple fields and those
with defined callbacks.
Paul Holden