Merge pull request #795 from 3d-gussner/MK3_fix5

Fix warning: This is kind of important

Firmware/Marlin_main.cpp

@@ -3291,10 +3291,10 @@ void process_commands()
             if( !(code_seen('X') || code_seen('Y') || code_seen('Z')) && code_seen('E')) {
               float echange=destination[E_AXIS]-current_position[E_AXIS];
 
-              if((echange<-MIN_RETRACT && !retracted) || (echange>MIN_RETRACT && retracted)) { //move appears to be an attempt to retract or recover
+              if((echange<-MIN_RETRACT && !retracted[active_extruder]) || (echange>MIN_RETRACT && retracted[active_extruder])) { //move appears to be an attempt to retract or recover
                   current_position[E_AXIS] = destination[E_AXIS]; //hide the slicer-generated retract/recover from calculations
                   plan_set_e_position(current_position[E_AXIS]); //AND from the planner
-                  retract(!retracted);
+                  retract(!retracted[active_extruder]);
                   return;
               }