* Added boards constants for LED_BUILTIN and KEY_BUILTIN Sources: * esp320: http://wiki.sweetpeas.se/index.php?title=ESP320#Developing_using_the_Arduino_IDE * esp32thing: https://cdn.sparkfun.com/assets/learn_tutorials/5/0/7/esp32-thing-schematic.pdf * espea32: https://github.com/AprilBrother/ESPea32/blob/master/hardware/ESPea32-schematic.pdf * hornbill32dev: https://github.com/ExploreEmbedded/Hornbill-ESP32-DEV/blob/master/Design%20Files/Schematic/Hornbill%20Devboard.pdf * lolin32: values from existing header * nano32: http://iot-bits.com/closer-look-esp32-nano32/ * node32s: https://github.com/lamloei/node32s-book/blob/master/ch01/node32s-schematic.pdf * Replace BUILTIN_LED constant with #define
