Cent/UCent as library types

[monarch_dodra]

I'm asking this as a end user:

It was my understanding that cent/ucent where more or less 
abandoned as native types. But would it be possible to have 
Cent/UCent as library types?

We have Complex, and Walter recently proposed the HalfFloat type.

Why not Cent and UCent?

Is it too complex for library code? I'd suspect you need to catch 
overflow flags for efficient carry over, but D has built-in asm, 
so that shouldn't be too complicated... Should it?

Or do we already have some sort of generic (statically sized) big 
inter, eg:
Big!128 or UBig!128? Or if not, would we want that?

Should I open an ER for either of the two ideas?