Minor bug fixes.

- Bug fix for step and direction invert masks not immediately being in
effect. Now regenerates the masks when a user changes this setting.

- Bug fix for probing cycle. G-code standard mandates that there is an
error if the probe is already triggered when the cycle is commanded.
However, Grbl may have motions to pull off a previous probing cycle in
queue and can falsely lead to errors. To fix this, the triggered check
is performed within the probing cycle itself, right after the planner
buffer is synced. If there is an error, it will now alarm out as a
probe fail.

gcode.c

@@ -795,10 +795,11 @@ uint8_t gc_execute_line(char *line)
           break;
         case MOTION_MODE_PROBE:
           // [G38 Errors]: Target is same current. No axis words. Cutter compensation is enabled. Feed rate
-          //   is undefined. Probe is triggered.
+          //   is undefined. Probe is triggered. NOTE: Probe check moved to probe cycle. Instead of returning
+          //   an error, it issues an alarm to prevent further motion to the probe. It's also done there to 
+          //   allow the planner buffer to empty and move off the probe trigger before another probing cycle.
           if (!axis_words) { FAIL(STATUS_GCODE_NO_AXIS_WORDS); } // [No axis words]
           if (gc_check_same_position(gc_state.position, gc_block.values.xyz)) { FAIL(STATUS_GCODE_INVALID_TARGET); } // [Invalid target]
-          if (probe_get_state()) { FAIL(STATUS_GCODE_PROBE_TRIGGERED); } // [Probe triggered]
           break;
       } 
     }