HAL for open-loop encoder homing

For reference, here are some results showing a comparison between the original proximity switch homing and the "index gated" implementation.
 
The "optimisation" process produced the biggest improvements which were the result of finessing the PID values and slightly reducing the homing speed to minimise the delay between reading the index pulse and processing the data. Both methods were significantly improved this way but the end results were almost identical.
For the test setup, I repeatedly homed the machine (typically 20 times, as shown), with the absolute position automatically logged and plotted.