Add TOTP (RFC6238) one-time password support

[Kevin Cernekee]

On Thu, Mar 21, 2013 at 5:37 AM, David Woodhouse <dwmw2 at infradead.org> wrote:
> On Mon, 2013-03-18 at 23:53 -0400, John Morrissey wrote:
>>
>> +#ifdef LIBOATH_HDR
>> +#include LIBOATH_HDR
>> +#endif
>> +
>
> Do you ever envisage that being set to anything other than
> <liboath/oath.h>? If not, let's change the macro to HAVE_OATH and just
> hard-code the #include <liboath/oath.h>?
>
> The same goes for LIBSTOKEN_HDR, in fact. Kevin? Unless either of you
> object, I'll make that change for both of them...

That's fine with me.