std.rational?

[Joseph Rushton Wakeling]

On 30/09/13 19:39, Joseph Rushton Wakeling wrote:
> ... although the new gcf will fail if passed immutable/const BigInts.

On this note: http://d.puremagic.com/issues/show_bug.cgi?id=11148

I had to tweak CommonInteger to handle immutable/const BigInts, and I'm not sure 
whether this was done correctly, although it seems to be largely in line with 
how CommonType works.