FONA SMS Notifications

This release adds:

• fona_sms_response.py: Example which waits for a SMS message from the FONA, reads it out and replies back to the sender. Similar to FONA_SMS_Response.ino in the arduino fona library.
• fona.enable_sms_notification: Getter/setter properties for FONA sms notification command
• fona.in_waiting: Returns number of bytes available to be read from the uart (https://circuitpython.readthedocs.io/en/latest/shared-bindings/busio/UART.html#busio.UART.in_waiting)
• NOTE: The _read_line() method has been changed to read_line()

To use in CircuitPython, simply install the Adafruit CircuitPython bundle.

To use in CPython, pip install adafruit-circuitpython-fona .

Read the docs for info on how to use it.