### Cores have been moved
Originally, the main Arduino repository contained Arduino
platforms/cores in this directory. Since then, these have been moved to
their own repositories instead (see commit 2e98854 and d6b40d0).

The official Arduino cores can now be found here:
 - https://github.com/arduino/ArduinoCore-avr
 - https://github.com/arduino/ArduinoCore-sam
 - https://github.com/arduino/ArduinoCore-samd