dud: A dub replacement

[Robert Schadek]

On Tuesday, 19 November 2019 at 16:30:26 UTC, Steven 
Schveighoffer wrote:
> And I would complain that the fact json exists as a file format 
> already screws up dub add -- using dub add removes ALL comments 
> in an SDL file, and rewrites the file in the order it sees fit.
>
> result: I don't use dub add any more.
>
> -Steve

I haven't implemented dud add yet, but it should be as easy as
parsing the file checking if the dep is already in.
If it is not the case add a new line to the end of the file.
dub.sdl files have no order after all.