Added an error code for laser mode when VARIABLE_SPINDLE is disabled.

- When trying to enable laser mode with $32=1 and VARIABLE_SPINDLE is
disabled, the error code shown was improperly stating it was a homing
failure. Added an new error code specifically for the laser mode being
disabled without VARIABLE_SPINDLE.

grbl/grbl.h

@@ -23,7 +23,7 @@
 
 // Grbl versioning system
 #define GRBL_VERSION "1.1f"
-#define GRBL_VERSION_BUILD "20170302"
+#define GRBL_VERSION_BUILD "20170324"
 
 // Define standard libraries used by Grbl.
 #include <avr/io.h>

grbl/report.h

@@ -38,6 +38,7 @@
 #define STATUS_LINE_LENGTH_EXCEEDED 14
 #define STATUS_TRAVEL_EXCEEDED 15
 #define STATUS_INVALID_JOG_COMMAND 16
+#define STATUS_SETTING_DISABLED_LASER 17
 
 #define STATUS_GCODE_UNSUPPORTED_COMMAND 20
 #define STATUS_GCODE_MODAL_GROUP_VIOLATION 21

grbl/settings.c

@@ -294,7 +294,7 @@ uint8_t settings_store_global_setting(uint8_t parameter, float value) {
           if (int_value) { settings.flags |= BITFLAG_LASER_MODE; }
           else { settings.flags &= ~BITFLAG_LASER_MODE; }
         #else
-          return(STATUS_SETTING_DISABLED);
+          return(STATUS_SETTING_DISABLED_LASER);
         #endif
         break;
       default: