Update lfe_scan.xrl

Made integer with base 2 ~ 36 work like Erlang.
Before change:
> #36rgg
exception exit: #(error #(1 lfe_scan #(user "illegal based number")) 1)
  in (lfe_io scan_and_parse 3)
  in (lfe_shell server_loop 1)
  in (erl_eval do_apply 6)
  in (shell exprs 7)
  in (shell eval_exprs 7)
  in (shell eval_loop 3)

After the change:
> #36rgg
592