This patch improves Elisp compatibility.

I added support for binary, octal, hexadecimal and arbitrary radix
integer literals as described in Elisp manual [1], except for the final
period. It should not take long to add support for the final period, but
in this patch I did not do this because Emacs itself does not support
final period for non-decimal integers.

[1]: https://www.gnu.org/software/emacs/manual/html_node/elisp/Integer-Basics.html