Fix min_resolved_spokes: use correct parser keyword instead of
thermal_spoke_width, generate bare number without units or (min)
wrapper, and load value without mm conversion.
Differentiate MINIMUM_TRACK_WIDTH from ROUTING_WIDTH on reload by
checking whether opt/max are present in the parsed constraint.
Update test expectation and add ROUTING_WIDTH round-trip test.
Damjan Prerad
7235b28feb