[Ironruby-core] Float parsing is culture dependent (patch included)

[John Lam (DLR)]

Thibaut Barrère:

> if you type "1.0" then enter under rbx on a french machine (or any
> machine with something different than dot for the decimal separator),
> you'll get an exception.
>
> I've attached a patch which works for me.

Thanks for sending in this patch! I'll make sure this makes it into our next push.

-John