Sort calculation results of a historical discharge calculation based on their start date. Therefore, there are two new inner classes TimerangeItem and HistoricalTimerangeItem that wrap a W, Q, Timerange (and delta Q). WQTimerange and HistoricalWQTimerange now implement a sort() that return the results (TimerangeItem or HistoricalWQTimerangeItem) sorted by their start date.

select.abflusstafel = SELECT ABFLUSSTAFEL_NR, \
                             ABFLUSSTAFEL_BEZ, \
                             GUELTIG_VON, \
                             GUELTIG_BIS, \
                             PEGELNULLPUNKT FROM ABFLUSSTAFEL WHERE MESSSTELLE_NR LIKE :number