add mrbc -h option

I expected, 

```bash
$ ./bin/mrbc -h
Usage: ./bin/mrbc [switches] programfile
  switches:
  -c           check syntax only
  -o<outfile>  place the output into <outfile>
  -v           print version number, then turn on verbose mode
  -g           produce debugging information
  -B<symbol>   binary <symbol> output in C language format
  --verbose    run at verbose mode
  --version    print the version
  --copyright  print the copyright
```

but cause this show.

```bash
$ ./bin/mrbc -h
./bin/mrbc: cannot open program file. (-h)
```