SPI access to multiple ToF sensors is working

I've been ploughing through the steps towards my goal of connecting multiple distance sensors to Anastasia's micro:bit.

I now have a pair of Arduinos connected via SPI, with the slave reporting distances from two VL53L0X sensors.

The wiring is a mess and the code needs cleaning up.

But it's working, and replacing the Arduino master by a micro:bit should be pretty straightforward.

I'll report on progress.

The code is on GitHub.