Fix Modbus address offset calculation bug that incorrectly associated
results with the wrong addresses.
Add explicit parentheses to avoid ambiguity.
Rename ampHoursToday to ampHourReading for consistency with
wattHourReading.
Add backwards-compat setter method.
When logging Modbus addresses, print them as hex integers.
Report calculated watts in toString(), in case pvAmps and pvVolts are
being used.
Remove daily offset calculations, to be consistent with wattHourReading.