M600: move extruder 100mm to the left to make space for opening idler

Firmware/Marlin_main.cpp

@@ -2956,8 +2956,13 @@ static void gcode_M600(bool automatic, float x_position, float y_position, float
         lcd_change_fil_state = lcd_show_fullscreen_message_yes_no_and_wait_P(_i("Was filament unload successful?"),
                 false, true); ////MSG_UNLOAD_SUCCESSFUL c=20 r=2
         if (lcd_change_fil_state == 0)
-            lcd_show_fullscreen_message_and_wait_P(_i("Please open idler and remove filament manually."));////MSG_CHECK_IDLER c=20 r=4
-        lcd_update_enable(true);
+		{
+			current_position[X_AXIS] -= 100;
+			plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS],
+				current_position[E_AXIS], FILAMENTCHANGE_XYFEED, active_extruder);
+			lcd_show_fullscreen_message_and_wait_P(_i("Please open idler and remove filament manually."));////MSG_CHECK_IDLER c=20 r=4
+			lcd_update_enable(true);
+		}
     }
 
     if (mmu_enabled)