Support LM75 temperature sensor (#1327)

* First draft of LM75 sensor based on HTU21 sensor

* Initialise I2C on ESP8266

* Add LM75 sensor to test builds

So that it will be tested with the continuous integration

platformio.ini

@@ -140,6 +140,7 @@ emodbus =  miq19/eModbus@1.0.0
 gfSunInverter = https://github.com/BlackSmith/GFSunInverter.git#v1.0.1
 decoder = https://github.com/theengs/decoder.git#v0.9.5
 ssd1306 = thingpulse/ESP8266 and ESP32 OLED driver for SSD1306 displays@^4.3.0
+lm75 = jeremycole/I2C Temperature Sensors derived from the LM75@^1.0.3
 
 [env]
 framework = arduino
@@ -253,6 +254,7 @@ lib_deps =
   ${libraries.bme280}
   ${libraries.bmp180}
   ${libraries.htu21}
+  ${libraries.lm75}
   ${libraries.ahtx0}
   ${libraries.unifiedsensor}
   ${libraries.dht}
@@ -1014,6 +1016,7 @@ lib_deps =
   ${libraries.bme280}
   ${libraries.bmp180}
   ;${libraries.htu21}
+  ${libraries.lm75}
   ${libraries.ahtx0}
   ${libraries.unifiedsensor}
   ${libraries.dht}