Amendments to the column class allow reports/entities to specify these
options for column instances, which are then passed to the aggregation
type when it is applied.
This allows each class to define the type of data that they return,
regardless of the type of column to which they are applied. This is the
pre-cursor to work on graphing and filtering of aggregated data.
E.g. a text field that is aggregated with "count" is returning numeric
data rather than text.
Paul Holden