Update I2C addresses of HAL devices to type I2CAddress (to support extended address functions).
Cast I2CAddress variables in DIAG calls to (int).
Remove uses of max() function (not available on some platforms.
Change I2C addresses from uint8_t to I2CAddress, in preparation for MUX support. Currently, by default, I2CAddress is typedef'd to uint8_t.
MUX support implemented for AVR and Wire versions.
Performance enhancements in IODevice::loop() function.
Improved error handling, device is placed off line if not responding.
Improved error reporting, device shown as offline if not operational (faulty or not present).
HAL Driver for VL53L0X Time-Of-Flight sensor. Basic implementation, which doesn't include most of the calibration etc. so is very lean on memory and CPU but not as accurate as it could be.
