Soft limit error bug fix.

- Soft limit errors were stuck in a feed hold without notifying the
user why it was in a hold. When resumed, the soft limit error would
kick in. Issue should be fixed to behave as intended. To automatically
hold and issue a soft limit alarm once the machine has come to a stop.

grbl/main.c

@@ -80,6 +80,7 @@ int main(void)
     sys_rt_exec_state = 0;
     sys_rt_exec_alarm = 0;
     sys.suspend = false;
+    sys.soft_limit = false;
           
     // Start Grbl main loop. Processes program inputs and executes them.
     protocol_main_loop();