(issue1755) Do not create interpolated themes and disable export of non interpolatable data. Due to the fact that data can contain NaN's which will be filtered out before creating the interpolator this requires the actual check for interpolatable data when data is set in the ResultValue

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