Re-factored system states and alarm management. Serial baud support greater than 57600.

- Refactored system states to be more clear and concise. Alarm locks
processes when position is unknown to indicate to user something has
gone wrong.

- Changed mc_alarm to mc_reset, which now manages the system reset
function. Centralizes it.

- Renamed '$X' kill homing lock to kill alarm lock.

- Created an alarm error reporting method to clear up what is an alarm:
message vs a status error: message. For GUIs mainly. Alarm codes are
negative. Status codes are positive.

- Serial baud support upto 115200. Previous baudrate calc was unstable
for 57600 and above.

- Alarm state locks out all g-code blocks, including startup scripts,
but allows user to access settings and internal commands. For example,
to disable hard limits, if they are problematic.

- Hard limits do not respond in an alarm state.

- Fixed a problem with the hard limit interrupt during the homing
cycle. The interrupt register is still active during the homing cycle
and still signal the interrupt to trigger when re-enabled. Instead,
just disabled the register.

- Homing rate adjusted. All axes move at homing seek rate, regardless
of how many axes move at the same time. This is unlike how the stepper
module does it as a point to point rate.

- New config.h settings to disable the homing rate adjustment and the
force homing upon powerup.

- Reduced the number of startup lines back down to 2 from 3. This
discourages users from placing motion block in there, which can be very
dangerous.

- Startup blocks now run only after an alarm-free reset or after a
homing cycle. Does not run when $X kill is called. For satefy reasons

report.h

@@ -29,27 +29,32 @@
 #define STATUS_ARC_RADIUS_ERROR 4
 #define STATUS_MODAL_GROUP_VIOLATION 5
 #define STATUS_INVALID_STATEMENT 6
-#define STATUS_HARD_LIMIT 7
-#define STATUS_SETTING_DISABLED 8
-#define STATUS_SETTING_VALUE_NEG 9
-#define STATUS_SETTING_STEP_PULSE_MIN 10
-#define STATUS_SETTING_READ_FAIL 11
-#define STATUS_IDLE_ERROR 12
-#define STATUS_ABORT_CYCLE 13
-#define STATUS_HOMING_LOCK 14
+#define STATUS_SETTING_DISABLED 7
+#define STATUS_SETTING_VALUE_NEG 8
+#define STATUS_SETTING_STEP_PULSE_MIN 9
+#define STATUS_SETTING_READ_FAIL 10
+#define STATUS_IDLE_ERROR 11
+#define STATUS_ALARM_LOCK 12
 
-// Define Grbl feedback message codes. Less than zero to distinguish message from error.
-#define MESSAGE_CRITICAL_EVENT -1
-#define MESSAGE_HOMING_ALARM -2
-#define MESSAGE_ENABLED -3
-#define MESSAGE_DISABLED -4
-#define MESSAGE_HOMING_UNLOCK -5
+// Define Grbl alarm codes. Less than zero to distinguish alarm error from status error.
+#define ALARM_HARD_LIMIT -1
+#define ALARM_ABORT_CYCLE -2
+
+// Define Grbl feedback message codes.
+#define MESSAGE_CRITICAL_EVENT 1
+#define MESSAGE_ALARM_LOCK 2
+#define MESSAGE_ALARM_UNLOCK 3
+#define MESSAGE_ENABLED 4
+#define MESSAGE_DISABLED 5
 
 // Prints system status messages.
 void report_status_message(uint8_t status_code);
 
+// Prints system alarm messages.
+void report_alarm_message(int8_t alarm_code);
+
 // Prints miscellaneous feedback messages.
-void report_feedback_message(int8_t message_code);
+void report_feedback_message(uint8_t message_code);
 
 // Prints welcome message
 void report_init_message();