Speeding up importing Phobos files

[Stefan Koch]

On Saturday, 19 January 2019 at 08:45:27 UTC, Walter Bright wrote:
> Andrei and I were talking on the phone today, trading ideas 
> about speeding up importation of Phobos files. Any particular D 
> file tends to import much of Phobos, and much of Phobos imports 
> the rest of it. We've both noticed that file size doesn't seem 
> to matter much for importation speed, but file lookups remain 
> slow.
>
> [...]

If we are going there we might as well use a proper database as 
the compiler cache format.
similar to to pre-compiled headers.

I'd be interested to see in how this bears out.
I am going to devote some time this weekend to it.

But using sqlite rather than zip.