Refactor and optimize Stepper/Planner

Better encapsulation and considerably reduce stepper jitter

Marlin/src/gcode/control/M80_M81.cpp

@@ -95,7 +95,7 @@
  */
 void GcodeSuite::M81() {
   thermalManager.disable_all_heaters();
-  stepper.finish_and_disable();
+  planner.finish_and_disable();
 
   #if FAN_COUNT > 0
     for (uint8_t i = 0; i < FAN_COUNT; i++) fanSpeeds[i] = 0;