Support for BME280 Temperature Correction (#1062)

* Support for BME280 Temperature Correction

The Spark Fun BME 280 library has support for Temperature correction, and this pull request implements the ability to apply a correction via a compiler directive ( BME280Correction ).

platformio.ini

@@ -236,6 +236,7 @@ build_flags =
   '-DZsensorADC="ADC"'
   '-DZsensorBH1750="BH1750"'
   '-DZsensorBME280="BME280"'
+  '-DBME280Correction=-3.4'
   '-DZsensorHTU21="HTU21"'
   '-DZsensorAHTx0="AHTx0"'
   '-DZsensorTSL2561="TSL2561"'