Remove real type

[Don]

bearophile wrote:
> I suggest to remove the real type from D2 because:
> - It's the only native type that has not specified length. I'm sold on the usefulness of having defined length types. 

The immediate problem is, that x87 does not fully support floats and 
doubles. It ONLY supports 80-bit reals.

Personally, I think it would be better if it were called real80 (even 
__real80), and if std.object contained
  alias real80 real;

The reason for this, is that it's quite reasonable for a 64-bit x86 
compiler to use 64-bit reals, and use SSE2 exclusively. However, even 
then, you want real80 to still be available.