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/gcode.c

@@ -901,7 +901,7 @@ uint8_t gc_execute_line(char *line)
   if (gc_state.spindle_speed != gc_block.values.s) {
     #ifdef VARIABLE_SPINDLE
       // Do not stop motion if in laser mode and a G1, G2, or G3 motion is being executed.
-      if ( !(bit_istrue(settings.flags,BITFLAG_LASER_MODE) && (axis_command == AXIS_COMMAND_MOTION_MODE) &&
+      if ( (bit_isfalse(settings.flags,BITFLAG_LASER_MODE) && (axis_command == AXIS_COMMAND_MOTION_MODE) &&
           ((gc_block.modal.motion == MOTION_MODE_LINEAR ) || (gc_block.modal.motion == MOTION_MODE_CW_ARC) || (gc_block.modal.motion == MOTION_MODE_CCW_ARC)) ) ) {
         // Update running spindle only if not in check mode and not already enabled.
         if (gc_state.modal.spindle != SPINDLE_DISABLE) { spindle_run(gc_state.modal.spindle, gc_block.values.s); }