[dev] [kronolith-patch] remove warning in exported CSV

[Chuck Hagenbuch]

Quoting Francois Marier <francois at nit.ca>:

> The Kronolith export function dumps a PHP warning in the resulting CSV
> file.
>
> This patch removes the warning, although I'm sure there's something
> better than "!($start_date === 0)"...

Yup, just setting $startInterval to null by default. Fixed, thanks. :)

-chuck

--
"Regard my poor demoralized mule!" - Juan Valdez