DMD 1.021 and 2.004 releases

[Walter Bright]

Don Clugston wrote:
> 1.020 seemed to be stable. Like 1.016, it was around for a long time, 
> and therefore particularly well tested. There were some great bug fixes 
> in 1.018 and 1.019.

Done.

> There's that substantive change about .init which happened in 1.017. If 
> that's permanent, it'd be good to stop further development relying on 
> the old behaviour.
> I think we need a policy for when the 'stable version' should be updated.
> 
> 
> Also, I don't see any mention of delimited string literals in the 
> changelog. <g>

Fixed.