- fixed all the laser preprocessors to work correctly and the resulting GCode to be plotted

- made sure that when drilling and milling with a `laser` preprocessor the first move is not done with the laser on

preprocessors/Marlin_laser_z.py

@@ -99,7 +99,8 @@ class Marlin_laser_z(PreProc):
 
     def lift_code(self, p):
         if float(p.laser_min_power) > 0.0:
-            return 'M3 S%s' % str(p.laser_min_power)
+            # the formatted text: laser OFF must always be like this else the plotting will not be done correctly
+            return 'M3 S%s ;laser OFF\n' % str(p.laser_min_power)
         else:
             gcode = 'M400\n'
             gcode += 'M5'
@@ -176,7 +177,8 @@ class Marlin_laser_z(PreProc):
 
     def spindle_stop_code(self, p):
         if float(p.laser_min_power) > 0.0:
-            return 'M3 S%s' % str(p.laser_min_power)
+            # the formatted text: laser OFF must always be like this else the plotting will not be done correctly
+            return 'M3 S%s ;laser OFF\n' % str(p.laser_min_power)
         else:
             gcode = 'M400\n'
             gcode += 'M5'