Correct SGP30ERR enum values - BREAKS BACKWARD COMPATIBILITY

To avoid compilation errors (conflicts) with other libraries which also use SUCCESS as an enumerated value, it was necessary to prefix the SGP30ERR enum values with SGP30_. SUCCESS becomes SGP30_SUCCESS etc..
Unfortunately this breaks backward compatibility.
If you start to see errors along the lines of SUCCESS being undefined, please use the Library Manager to select version 1.0.4 of this library.
Sorry about that...

Remove Wire.begin() from ::begin()

v1.0.4

Add wire.begin to example.

Updating Example3_Humidity

Updating Example 3 - Humidity to use the SHTC3 instead of the Si7021. Also added a conditional statement to the loop to allow users to update the humidity compensation value without resetting the circuit.

Fix Rhumidity bug. Remove extra qualifier from class def.

v1.0.2

Add thanks to in readme. Bump lib ver. touchup ex 3 whitespace.

v1.0.1

lib ver roll

Initial Release

v1.0.0

added comments