At least the BE and the NL DSMR devices use MBUS.
Therefor we make the MBUS obis reference generic, and convert the V5
telegram to use MBUS values.
Also remove BELGIUM_MAX_POWER_PER_PHASE as this was a duplicate.
Finally set self.maxDiff = None to have a full test output on some
tests.
* fix index offset for month timestamp in BELGIUM_MAXIMUM_DEMAND_13_MONTHS
* add timestamps to test case
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Co-authored-by: Emilio Jose Palacios Garcia <epalacio@emilio.esat.kuleuven.be>