'Override the onecmd method to:
- catch and print all exceptions
- allow for composite commands in interactive mode (foo; bar)
- call \'do_foo\' on plugins rather than ourself'

def onecmd(self, line):

    result = self.onecmd_run(line)
    if (self.options.exit_on_error and (self.exit_status is not None)):
        raise SystemExit(self.exit_status)
    return result
