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* FEATURE get_stat_data now applies the ``only`` and ``exclude`` parameters in the database. This makes it possible to specify filters on fields that don't need to be fetched.
* FIX get_stat_data now uses the ``denominator_key`` to determine the table total for FieldTables that have ``denominator_key`` specified.
* FIX correctly serialise Decimal() in additional places
* Don't use whitespace in JSON responses.