Add SHT30 Temp/Humidity Sensor support

[pidiet]

Hey,

this one is also great, small and more precise than dht22. And it has a wemos shield as well: https://wiki.wemos.cc/products:d1_mini_shields:sht30_shield

Notes:
Wemos' provided library is hinky and not recommended.
This firmware uses ClosedCube's library instead: https://github.com/closedcube/ClosedCube_SHT31D_Arduino (not closed at all!)
Source: https://github.com/boneskull/shtshow

[smrtnt]

Hi @pidiet,
One sensor has just been ordered.

[smrtnt]

Support added now for SHT3X sensors (cf. commit).

[rradar]

@mertenats thank's so much!

Just builded my first multi sensor with a sht30! Just works! Great!