PRD-4069 and PRD-4523

Validated PRD-4069 to ensure that streaming processing of table exports works. There is now an JUnit test for that condition, so whenever we break it, we will get an early warning.

Fixed PRD-4523, which was shown to be a problem thanks to one of Kurtis' complex reports, but ultimately it was caused by a rounding error in the reporting core and potentially affects all report layouts, relational and crosstab alike.