Si7021 - please add support for internal chip-heating

[umbm]

The P014_SI7021.ino does not support the internal heating of the chip.

Using the si7021-adafruit-library it is possible to activate the internal chip-heating if the humidity is very high (>75%) to increase the precision in outdoor use.
In this case the temperature rises 1.8 and this value has to be substracted form measured temperature.

Would be nice if this could be added to espeasy too.

[TD-er]

Correcting for heating isn't as simple as subtracting some offset from the temperature alone.
Do you know if the library also has a formula for that?

[umbm]

Yes I know. The recalculation of the temp offset isn't the problem.
The most important thing is to set the register to activate/deactivate the internal heater if necessary.

I took a look at the adafruit_Si7021.h library and it's in use from last version on there.

https://github.com/adafruit/Adafruit_Si7021