2019-06-17 0.4.0

Getting real

• Upgrade to Pycom MicroPython 1.20.0.rc11
• Stop leaking sensible information into settings output
• Improve documentation
• Switch to LittleFS
• Add deep sleep
• Improve Makefile targets
• Add more wakeup reasons
• Add missing configuration section for HX711 to settings example.
  Thanks, @ClemensGruber.
• Add basic device-interval sensors SystemTemperature and SystemBatteryLevel
• Explicitly shut down all peripherals having implicitly been turned on
• Add SystemWiFiMetrics sensor
• Add SystemUptime sensor
• Fix: Better explicitly initialize the ADC before reading it
• Improve SystemBatteryLevel sensor. Thanks, Dominik <https://github.com/ayoy>_!
• Make TelemetryTransportHTTP work again
• Improve telemetry subsystem re. multi-protocol and -topology. Enable HTTP telemetry.
• Add configuration example for BEEP-BOB settings.example-bob.py
• Honor "scale" and "offset" parameters when reading the HX711. Fix #6.
• Improve reading the HX711 re. wrong kg scaling.
  Transmit all raw values and settings of HX711.
• Attempt to improve #5: Reading Vcc.
• Add missing "topology" configuration settings attribute
  for MQTT telemetry to example configurations
• Fix deep sleep
• Conditionally start telemetry subsystem just if networking is available
• Improve robustness wrt. WiFi connectivity
• Improve log messages
• Bump version to 0.4.0dev
• Improve purging of sensible configuration settings
• SystemBatteryLevel: Obtain voltage divider parameters from settings
• Improve release tooling
• Improve error signalling for missing "topology" configuration setting