Fixed bug with daylight savings time on date pickers

One of our Canadian customers contacted us to report that the date pickers on the scheduling maintenance form were not correctly accounting for the recent change in daylight saving time.

After some diagnosis, we narrowed this down to a Javascript bug in the library we use to convert dates and times between time zones.

To keep the Javascript lightweight we only store the next few years worth of date thresholds when daylight savings time should and should not be applied to certain timezones.

We were using an outdated version of this database which meant the plugin was not able to determine if DST should be applied or not.

We have now updated the database, and the problem is fixed.