Registry schema cleanup

[Clemens Lang]

Hi,

----- On 18 Nov, 2014, at 23:34, Joshua Root jmr at macports.org wrote:


> SQLite considers NULLs to be distinct in this case.
> <https://www.sqlite.org/nulls.html>

Thank you, that's valuable information. Weird information, but still
valuable. That also explains why this hasn't caused any problems yet.
Anyway, in that case the `url' column is simply unused, and for that
reason I'd propose to remove it.

-- 
Clemens Lang