See feed-in values at a plant with no feed-in meter

Add a virtual feed-in meter and your plant shows grid power and lifetime feed-in energy added up from its inverters. A meter that reports power but keeps no energy counter gets its lifetime total this way too; if it goes quiet you lose detail, but no energy. Your plants receive this with their next agent update.

• An inverter that goes quiet credits its whole missed production with its first reading back.
• The lifetime total never falls back, and adding or replacing an inverter leaves it where it is.
• A jump larger than your plant could physically produce is not counted towards the total.
• Where a physical meter reports the value, that reading is used instead.