• the humidity and temperature attributes are direct access: they can now be read several times without requiring a request to the sensor.
• the is_busy method is replaced by is_ready and calls to this method become mandatory for temperature and humidity updates.

Add CRC control for the status.
CRC control is now used on all commands when enabled.

Major version: this version is not backward compatible: the status attribute is removed.

• replaces the status attribute by attributes more ergonomic for the user: is_busy and is_calibrated.
• makes a calibration after reset if necessary.
• Fixes:
  • a major bug on the reset function systematically produced a fatal error

optimization: Request the CRC byte only if necessary

Tested with MicroPython 1.17 on a Wemos D1 mini Lite card (with 1MB flash and based on ESP-8285) and an AHT21 sensor.