D const design rationale

[Jeff Nowakowski]

Walter Bright wrote:
> readonly is a synonym for const, so no improvement there.

I think readonly is a much better mnemonic than const, especially 
considering that const is often explained in terms of being a read-only 
view.  Yes, invariant can be described in terms of read-only too, but 
const vs invariant look *exactly* the same to me, whereas readonly doesn't.

-Jeff