Make Gen7 1.4 heater pins match silkscreen
Add (as an option) slower SD transfer mode
fix DEFAULT_AXIS_STEPS_PER_UNIT minor Z rounding error
Solved minor bug in controllerFan()

Extruder 2 was checked where extruder 1 should be checked.
fixed wrong compare for min temp check of heater 1 and heater 2
fixed/optimized pins.h for RUMBA when using multiple extruders