Added grbl planner Matlab simulator for test reference. Updated line number compile-time option.

- Added a grbl planner simulation tool that was written in Matlab and
Python. It was used to visualize the inner workings of the planner as a
program is streamed to it. The simulation assumes that the planner
buffer is empty, then filled, and kept filled. This is mainly for users
to see how the planner works.

- Updated some of the compile-time ifdefs when enabling line numbers.
The leaving the un-used line numbers in the function calls eats a
non-neglible amount of flash memory. So the new if-defs remove them.

motion_control.h

@@ -24,18 +24,26 @@
 
 #define HOMING_CYCLE_LINE_NUMBER -1
 
-
 // Execute linear motion in absolute millimeter coordinates. Feed rate given in millimeters/second
 // unless invert_feed_rate is true. Then the feed_rate means that the motion should be completed in
 // (1 minute)/feed_rate time.
+#ifdef USE_LINE_NUMBERS
 void mc_line(float *target, float feed_rate, uint8_t invert_feed_rate, int32_t line_number);
+#else
+void mc_line(float *target, float feed_rate, uint8_t invert_feed_rate);
+#endif
 
 // Execute an arc in offset mode format. position == current xyz, target == target xyz, 
 // offset == offset from current xyz, axis_XXX defines circle plane in tool space, axis_linear is
 // the direction of helical travel, radius == circle radius, isclockwise boolean. Used
 // for vector transformation direction.
+#ifdef USE_LINE_NUMBERS
 void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8_t axis_1,
   uint8_t axis_linear, float feed_rate, uint8_t invert_feed_rate, float radius, uint8_t isclockwise, int32_t line_number);
+#else
+void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8_t axis_1,
+  uint8_t axis_linear, float feed_rate, uint8_t invert_feed_rate, float radius, uint8_t isclockwise);
+#endif
   
 // Dwell for a specific number of seconds
 void mc_dwell(float seconds);