New alarm method. Re(re)organized status messages.

- Installed a new 'alarm' method to centralize motion kills across
alarm or reset events. Right now, this is controlled by system abort
and hard limits. But, in the future, a g-code parser error may call
this too as a safety feature.

- Re(re)organized status messages to just print all errors, regardless
from where it was called. This centralizes them into one place.

- Misc messages method installed for any user feedback that is not a
confirmation or error. Mainly so that there is a place to perform
warnings and such.

- New stuff installed and still made the flash size smaller by saving
flash space from clearing out repeated '\r\n' pgmstrings.

- Fixed a bug where hard limits message would print everytime a system
abort was sent.

protocol.h

@@ -21,28 +21,31 @@
 #ifndef protocol_h
 #define protocol_h
 
-
+// Line buffer size from the serial input stream to be executed.
+// NOTE: Not a problem except for extreme cases, but the line buffer size can be too small
+// and g-code blocks can get truncated. Officially, the g-code standards support up to 256
+// characters. In future versions, this will be increased, when we know how much extra
+// memory space we can invest into here or we re-write the g-code parser not to have his 
+// buffer.
 #define LINE_BUFFER_SIZE 50
 
 // Define Grbl status codes.
 #define STATUS_OK 0
-// Critical error codes. Greater than zero.
 #define STATUS_BAD_NUMBER_FORMAT 1
 #define STATUS_EXPECTED_COMMAND_LETTER 2
 #define STATUS_UNSUPPORTED_STATEMENT 3
 #define STATUS_FLOATING_POINT_ERROR 4
 #define STATUS_MODAL_GROUP_VIOLATION 5
 #define STATUS_INVALID_STATEMENT 6
-#define STATUS_SETTING_DISABLED 7
-#define STATUS_HARD_LIMIT 8
-// Non-critical error codes. Less than zero.
-#define STATUS_SETTING_INVALID -1
-#define STATUS_SETTING_STEPS_NEG -2
-#define STATUS_SETTING_STEP_PULSE_MIN -3
+#define STATUS_HARD_LIMIT 7
+#define STATUS_SETTING_DISABLED 8
+#define STATUS_SETTING_STEPS_NEG 9
+#define STATUS_SETTING_STEP_PULSE_MIN 10
+#define STATUS_SETTING_READ_FAIL 11
+
+// Define Grbl misc message codes
+#define MESSAGE_HOMING_ENABLE 1
 
-// Define Grbl warning message codes
-#define WARNING_HOMING_ENABLE 1
-#define WARNING_SETTING_READ_FAIL 2
 
 // Initialize the serial protocol
 void protocol_init();
@@ -52,12 +55,15 @@ void protocol_init();
 void protocol_process();
 
 // Executes one line of input according to protocol
-int8_t protocol_execute_line(char *line);
+uint8_t protocol_execute_line(char *line);
 
 // Checks and executes a runtime command at various stop points in main program
 void protocol_execute_runtime();
 
-// Prints any warning messages.
-void protocol_warning_message(int8_t warning_code);
+// Prints Grbl's status messages.
+void protocol_status_message(uint8_t status_code);
+
+// Prints any misc messages.
+void protocol_misc_message(uint8_t message_code);
 
 #endif