Make uploaded data configurable

[enwi]

Currently only power generation (v2), power consumption (v4) and battery voltage (v6) are uploaded to PVOutput, which cannot be changed, but it would make more sense to give the user more options to choose from. This makes even more sense if they donated and have access to bonus features (v7-v12 and m1).

All possible parameters that can be uploaded can be found here.

First proposal:

• Let user choose between battery voltage and panel voltage for parameter v6 (load voltage is left out, because it is essentially the same as battery voltage)
• Let user choose between battery temperature and controller temperature for paramter v5