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 ).

main/config_BME280.h

@@ -62,4 +62,16 @@ int BME280_i2c_addr = 0x76; // Bosch BME280 I2C Address
 int BME280_PIN_SDA = SDA; // PIN SDA
 int BME280_PIN_SCL = SCL; // PIN SCL
 
+// Temperature correction for BME280 devices
+
+#ifndef BME280Correction
+
+// BME280Correction - Correction in celcius of temperature reported by bme280 sensor.  Both Celcius and Farenheit temperatures are adjusted.
+// -------------------------
+// Value is a float
+// ie Compiler Directive '-DBME280Correction=-3.4'
+
+#  define BME280Correction 0
+#endif
+
 #endif