Add BME680 demo app

Demo App which shows Temperature, Humidity and Pressure. Updates every 10 secs.

preload/apps/bme680_sensor_demo/__init__.py

+"""
+BME680 Demo
+===========
+This app shows the current readings of the BME680 sensor
+"""
+import buttons
+import color
+import display
+import os
+import utime
+import bme680
+
+
+def main():
+    bme680.init()
+
+    disp = display.open()
+    disp.clear().update()
+
+    while True:
+        sensor_data = bme680.get_data()
+        disp.clear()
+        disp.print("BME680 Sensor")
+        disp.print("{} C".format(str(sensor_data[0])), posy=20)
+        disp.print("{} rh".format(str(sensor_data[1])), posy=40)
+        disp.print("{} hPa".format(str(sensor_data[2])), posy=60)
+        disp.update()
+        utime.sleep(10)
+
+
+if __name__ == "__main__":
+    main()