std.rational -- update and progress towards review

[Joseph Rushton Wakeling]

On Friday, 4 October 2013 at 18:56:35 UTC, Walter Bright wrote:
> On 10/2/2013 7:25 AM, Joseph Rushton Wakeling wrote:
>> Anyway, I'd really value your feedback at this point.
>
> To add to your burdens :-) please also run a -cov -unittest 
> -main, and determine the unittest coverage. Please shoot for >= 
> 95% coverage. 100% is even better!

It is 95% -- I can always see if I can improve that :-)