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.

planner.h

@@ -51,9 +51,10 @@ typedef struct {
   float acceleration;            // Axis-limit adjusted line acceleration in (mm/min^2)
   float millimeters;             // The remaining distance for this block to be executed in (mm)
   // uint8_t max_override;       // Maximum override value based on axis speed limits
-#ifdef USE_LINE_NUMBERS
-  uint32_t line_number;
-#endif
+
+  #ifdef USE_LINE_NUMBERS
+    int32_t line_number;
+  #endif
 } plan_block_t;
 
       
@@ -63,7 +64,7 @@ void plan_reset();
 // Add a new linear movement to the buffer. target[N_AXIS] is the signed, absolute target position 
 // in millimeters. Feed rate specifies the speed of the motion. If feed rate is inverted, the feed
 // rate is taken to mean "frequency" and would complete the operation in 1/feed_rate minutes.
-void plan_buffer_line(float *target, float feed_rate, uint8_t invert_feed_rate, uint32_t line_number);
+void plan_buffer_line(float *target, float feed_rate, uint8_t invert_feed_rate, int32_t line_number);
 
 // Called when the current block is no longer needed. Discards the block and makes the memory
 // availible for new blocks.