(issue1801) Unify reference gauge finding code The basic way as described in the method comment of the determineRefGauge method is now used in the WINFOArtifact, MainValuesService and RiverUtils.getGauge method. RiverUtils.getGauge previously just returned the first gauge found. While this is now a behavior change I believe that it is always more correct then the undeterministic behavior of the previous implmenentation.

next.gauge.id = \
    SELECT GAUGES_ID_SEQ.NEXTVAL AS gauge_id FROM DUAL
next.timeinterval.id = \
    SELECT TIME_INTERVALS_ID_SEQ.NEXTVAL AS time_interval_id FROM DUAL
next.discharge.id = \
    SELECT DISCHARGE_TABLES_ID_SEQ.NEXTVAL AS discharge_table_id FROM DUAL
next.discharge.table.values.id = \
    SELECT DISCHARGE_TABLE_VALUES_ID_SEQ.NEXTVAL AS discharge_table_values_id FROM DUAL