v1.50.0
NRF52840 Changes:
- Support for non-mbed cores including Feather, Clue and most NRF52840 boards in general
- Support for more PDM sample rates: 16khz, 20khz, 31.25khz, 41.672khz
- Enable secondary output pin (enabled by editing AutoAnalogAudio.cpp #define DEFAULT_PWM_PIN2 )
- Update I2S code (this is probably as near to I2S working properly as its going to get)