ROCKSOLID-336. Fix issue with negative values for statistics when reprocessing messages. We did this all in memory (rather than editing sql calls) because values in the display were not being updated, even after manual refresh. Users affected by this bug will need to manually clear statistics to remove negative values.Statistics now has a new variable (allowNegatives) to control whether the object allows negative values or not. This is needed since some Statistics objects act as a 'diff' as opposed to being a counter for values.