[dev] Patch for kronolith js

[Chuck Hagenbuch]

Quoting Jason Rust <jrust at rustyparts.com>:

> The attached patch cleans up the javascript for calculating the duration
> a bit and fixes two bugs.  One bug occured when the duration of the
> event was greater than 365 days, the other occured when the duration was
> greater than the allowed end-date range.

Committed, thanks.

-chuck

--
Charles Hagenbuch, <chuck at horde.org>
The alligators were there, too, in a bathtub inside the house.