Improvements and fixes

Plant outages, device faults and event times now read as the devices ran. Outages no longer open from a zero combiner box reading, and event times no longer carry the timezone offset.

• A combiner box that reports zero power against its own live readings no longer opens an outage.
• A silent inverter now opens a plant alarm after 12 hours.
• Two data loggers can now be added, reading combiner boxes, strings, the grid meter, irradiation and temperature sensors, and curtailment limits.
• A plant-wide grid trip is no longer recorded as a device fault.
• Event times from the data logger are no longer off by the timezone offset.