Set the most recent event as current slide on plugin load.

In case the timeline implementation has lots of past and future events added, it would be most useful if the timeline could also have the ability to display the most recent future event (relative to the current time/date) as the current slide when the plugin loads.
For example, instead of start_at_end="false" or "true", we could have start_at="end"/"beginning"/"recent"
