Suggestion: Improve temp sensor adjustment method

[oopee]

Calibration curve of temperature sensors are often non-linear. The measurement error increases as the temperature approaches the max/min values the sensor can handle. Simple and constant adjustment value is usable only in relatively limited range of temperature values. Exact calibration calculations can be complicated and maybe not very practical in Domoticz. In some (many?) cases there is easy intermediate way: use percentage as adjustment value.

For example (loosely based on TFA sensor in my sauna):
Typical low value (sauna off):
26.5C, actual 27C, adjustment needed +0.5C

Typical high value (sauna on):
67.5C, actual 70C, adjustment needed +2.5C

With percentage adjustment with single value of 104% the adjusted values are 27.6C and 70.2C (27C/70C actual). Not perfect but maybe more acceptable than with simple offset value.

So the suggestion is to add 2nd optional adjustment value to temperature sensor settings which uses percentage value.