message: move the QUIT command to the list of commands that works even if no file is loaded yet
diff: @@ -251,6 +251,9 @@ fn cmd(op1: Option<&str>, op2: Option<&str>) {
  }
  return;
  }
  + (Some(command::QUIT), _) => {
  + process::exit(0);
  + }
  _ => {}
  };
  if proj_opt.borrow().is_none() {
  @@ -308,9 +311,6 @@ fn cmd(op1: Option<&str>, op2: Option<&str>) {
  println!("{} is not found", f);
  }
  }
  - (Some(command::QUIT), _) => {
  - process::exit(0);
  - }
  _ => {
  println!(
  "Invalid command {} {}",
  