v1.1c: New sleep mode. Laser mode and other bug fixes.

- New $SLP sleep mode that will disable spindle, coolant, and stepper
enable pins. Allows users to disable their steppers without having to
alter their settings. A reset is required to exit and re-initializes in
alarm state.

- Laser mode wasn’t updating the spindle PWM correctly (effected
spindle speed overrides) and not checking for modal states either.
Fixed both issues.

- While in laser mode, parking motions are ignored, since the power off
delay with the retract motion would burn the material. It will just
turn off and not move. A restore immediately powers up and resumes. No
delays.

- Changing rpm max and min settings did not update the spindle PWM
calculations. Now fixed.

- Increased default planner buffer from 16 to 17 block. It seems to be
stable, but need to monitor this carefully.

- Removed software debounce routine for limit pins. Obsolete.

- Fixed a couple parking motion bugs. One related to restoring
incorrectly and the other the parking rate wasn’t compatible with the
planner structs.

- Fixed a bug caused by refactoring the critical alarms in a recent
push. Soft limits weren’t invoking a critical alarm.

- Updated the documentation with the new sleep feature and added some
more details to the change summary.

grbl/settings.c

@@ -28,8 +28,6 @@ settings_t settings;
 void settings_store_startup_line(uint8_t n, char *line)
 {
   #ifdef FORCE_BUFFER_SYNC_DURING_EEPROM_WRITE
-    // TODO: Alter the startup line parsing to prevent motions from being executed before this call.
-    // Implement it like the jog parsing.
     protocol_buffer_synchronize(); // A startup line may contain a motion and be executing. 
   #endif
   uint32_t addr = n*(LINE_BUFFER_SIZE+1)+EEPROM_ADDR_STARTUP_BLOCK;
@@ -288,8 +286,8 @@ uint8_t settings_store_global_setting(uint8_t parameter, float value) {
       case 25: settings.homing_seek_rate = value; break;
       case 26: settings.homing_debounce_delay = int_value; break;
       case 27: settings.homing_pulloff = value; break;
-      case 30: settings.rpm_max = value; break;
-      case 31: settings.rpm_min = value; break;
+      case 30: settings.rpm_max = value; spindle_init(); break; // Re-initialize spindle rpm calibration
+      case 31: settings.rpm_min = value; spindle_init(); break; // Re-initialize spindle rpm calibration
       case 32:
         #ifdef VARIABLE_SPINDLE
           if (int_value) { settings.flags |= BITFLAG_LASER_MODE; }