Closed loop position recovery post power restoration

Currently if the logic power is left applied (e.g. via V_Aux on the 1HCL) and the main power is cut (e.g. due to an E-stop) when it is reapplied the closed loop control will revert to the motor position before the main power was lost. This could cause a sudden and large movement if the motors were moved, e.g. by hand, while main power was removed.

