Improvements and fixes

Lost energy during an inverter outage counts all of the inverter's strings, and plants with several feed-in meters are checked against their sum.

• During an inverter outage, lost energy now counts all of the inverter's strings, including strings whose own data stopped arriving during the outage.
• On plants with more than one feed-in meter, the feed-in check no longer compares each meter alone with the whole plant's expected output.