Fix of a loss in precission when the extruder multiplier is set

with M221. For 50um layers, the precision loss leads to holes
in the print.

Firmware/Marlin_main.cpp

@@ -6515,7 +6515,11 @@ void get_coordinates()
   for(int8_t i=0; i < NUM_AXIS; i++) {
     if(code_seen(axis_codes[i]))
     {
-      destination[i] = (float)code_value() + (axis_relative_modes[i] || relative_mode)*current_position[i];
+      destination[i] = (float)code_value();
+      if (i == E_AXIS && extrudemultiply != 100)
+        destination[i] *= (extrudemultiply * 0.01f);
+      if (axis_relative_modes[i] || relative_mode)
+        destination[i] += current_position[i];
       seen[i]=true;
     }
     else destination[i] = current_position[i]; //Are these else lines really needed?

Firmware/planner.cpp

@@ -784,10 +784,6 @@ block->steps_y = labs((target[X_AXIS]-position[X_AXIS]) - (target[Y_AXIS]-positi
   block->steps_e = labs(target[E_AXIS]-position[E_AXIS]);
   if (volumetric_multiplier[active_extruder] != 1.f)
     block->steps_e *= volumetric_multiplier[active_extruder];
-  if (extrudemultiply != 100) {
-    block->steps_e *= extrudemultiply;
-    block->steps_e /= 100;
-  }
   block->step_event_count = max(block->steps_x, max(block->steps_y, max(block->steps_z, block->steps_e)));
 
   // Bail if this is a zero-length block
@@ -919,7 +915,7 @@ Having the real displacement of the head, we can calculate the total movement le
     delta_mm[Y_AXIS] = ((target[X_AXIS]-position[X_AXIS]) - (target[Y_AXIS]-position[Y_AXIS]))/axis_steps_per_unit[Y_AXIS];
   #endif
   delta_mm[Z_AXIS] = (target[Z_AXIS]-position[Z_AXIS])/axis_steps_per_unit[Z_AXIS];
-  delta_mm[E_AXIS] = ((target[E_AXIS]-position[E_AXIS])/axis_steps_per_unit[E_AXIS])*volumetric_multiplier[active_extruder]*extrudemultiply/100.0;
+  delta_mm[E_AXIS] = ((target[E_AXIS]-position[E_AXIS])/axis_steps_per_unit[E_AXIS])*volumetric_multiplier[active_extruder];
   if ( block->steps_x <=dropsegments && block->steps_y <=dropsegments && block->steps_z <=dropsegments )
   {
     block->millimeters = fabs(delta_mm[E_AXIS]);