Minor bug fixes.

- G38.x was not printing correctly in the $G g-code state reports. Now
fixed.

- Potential bug regarding volatile variables inside a struct. It has
never been a problem in v0.9, but ran into this during v1.0
development. Just to be safe, the fixes are applied here.

- Updated pre-built firmwares with these two bug fixes.

grbl/report.c

@@ -331,7 +331,7 @@ void report_gcode_modes()
     case MOTION_MODE_NONE : printPgmString(PSTR("G80")); break;
     default: 
       printPgmString(PSTR("G38."));
-      print_uint8_base10(gc_state.modal.motion - (MOTION_MODE_PROBE_TOWARD+2));
+      print_uint8_base10(gc_state.modal.motion - (MOTION_MODE_PROBE_TOWARD-2));
   }
 
   printPgmString(PSTR(" G"));