Minor updates to line number feature.

- Changed line number integer types from unsigned to signed int32.
G-code mandates values cannot exceed 99999. Negative values can be used
to indicate certain modes.

- Homing cycle line number changed to -1, as an indicator.

- Fixed a reporting define for the spindle states that was broken by
the last merge.

motion_control.h

@@ -22,19 +22,20 @@
 #ifndef motion_control_h
 #define motion_control_h
 
-#define HOMING_CYCLE_LINE_NUMBER 1000000000
+#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.
-void mc_line(float *target, float feed_rate, uint8_t invert_feed_rate, uint32_t line_number);
+void mc_line(float *target, float feed_rate, uint8_t invert_feed_rate, int32_t line_number);
 
 // 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.
 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, uint32_t line_number);
+  uint8_t axis_linear, float feed_rate, uint8_t invert_feed_rate, float radius, uint8_t isclockwise, int32_t line_number);
   
 // Dwell for a specific number of seconds
 void mc_dwell(float seconds);