Fix problem in date picker of nothing happening when selecting year at end of date range

[akc42]

This fixes an issue whereby trying to use the year selector for a year at the end of the date range, if the calendar has not previously been set to ensure the date when the year is selected is within range, everything reverts to the old date.

This is confusing and frustrating to the user who may (I would say mostly, but that is just my way of thinking) select the year before going on to then select the date within the year.

[bendavis78]

While I agree the current behavior is probably undesirable, I think the same can be said if we implicitly set the date to the min/max as well. Ideally the user should be shown an error, or the developer should be able to handle invalid date values. I've created a new issue for this (#85). Feel free to continue discussion there.