Add license headers.
Add a define for Neopixel pin.
Add DS3231 driver.
Simple neopixel code for SAM D21.
Add license headers (ISC).
Fix warnings and rx logic.
Fix warning and array type.
Fix compilation.
Improve rx task.
Cleanups and a task for rx.
Sending and receiving works.
Drivers for various devices.

For now, only nRF24 driver.