SPI doesn't compile on ESP32

[sfe-SparkFro]

SparkFun_Toolkit/src/sfe_bus.cpp

Line 231 in 6ee3c24

SPISettings spiSettings = SPISettings(3000000, MSBFIRST, SPI_MODE3);

MSBFIRST and SPI_MODE3 not defined, might need to `#include <Arduino.h>

[gigapod]

fixed