Weirdness with numeric_limits in new special functions

[Paolo Carlini]

Hi Ed and thanks for quick replying,

> The public functions in std::tr1: call these with floating point types 
> only.

Ok.

> I think the errtol *is* a mistake because __eps / 8 will degenerate to 
> 0.  The errtol should wind up being rather larger than __eps.
>
> It might be a good idea to block calling with integral _Tp somehow.
>
> Actually, let me walk through the code and make sure what's going on.

Excellent. Take you time, but let's make sure everything is consistent. 
In any case, for now I'm not going to fiddle with the special functions.

Paolo.