At least the BE and the NL DSMR devices use MBUS.
Therefore we make the MBUS obis reference generic, and convert the V5
telegram to use MBUS values.
Finally set self.maxDiff = None to have a full test output on some
tests.
Sometimes peak usage is not yet visible in the 13 months history code.
It gives a 0.0kW value with timestamp (632525252525W).
Also the peak usage value can be invalid, handle this case also.
* 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>
