Load filament performs feed to FINDA and retract:
- engage idler
- feed normal to FINDA with config::feedToFinda distance until FINDA triggers
- retract normal and as soon FINDA un-triggers move back to PTFE config::cuttingEdgeToFindaMidpoint
- disengage the idler
That implied introducing another substate machine - RetractFromFinda, which does the opposite
of FeedToFinda while also checking for the FINDA switching off while retracting filament.
Still, ToolChange and CutFilament need fixing with this change
That implies changing motor's mode from SpreadCycle into StealtMode (or vice versa)
requires a stand still MMU with no other command (i.e. motor moves) being performed.
This elegantly solves the synchronization problem of TMC2130 mode change, as it results
in severe jerking while a motor is moving.
The change in protocol is minimal - M0/M1 first return `M0 A` (accepted) and another `Q0` then
returns `M0 F` (finished). The MK4 counterpart may ignore the additional report if necessary
as the mode change is done immediately (shortly after responding with `M0 A`)
D.R.racer
Alan Dragomirecký